text: 
  /* pngrtran.c - transforms the data in a row for PNG readers
   *
   * Last changed in libpng 1.4.5 [December 9, 2010]
   * Copyright (c) 1998-2010 Glenn Randers-Pehrson
   * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   *
   * This code is released under the libpng license.
   * For conditions of distribution and use, see the disclaimer
   * and license in png.h
   *
   * This file contains functions optionally called by an application
   * in order to tell libpng how to handle data when reading a PNG.
   * Transformations that are used in both reading and writing are
   * in pngtrans.c.
   */
  
  #define PNG_NO_PEDANTIC_WARNINGS
  #include "png.h"
  #ifdef PNG_READ_SUPPORTED
  #include "pngpriv.h"
  
  /* Set the action on getting a CRC error for an ancillary or critical chunk. */
  void PNGAPI
  png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
  {
     png_debug(1, "in png_set_crc_action");
  
     if (png_ptr == NULL)
        return;
  
     /* Tell libpng how we react to CRC errors in critical chunks */
     switch (crit_action)
     {
        case PNG_CRC_NO_CHANGE:                        /* Leave setting as is */
           break;
  
        case PNG_CRC_WARN_USE:                               /* Warn/use data */
           png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
           png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
           break;
  
        case PNG_CRC_QUIET_USE:                             /* Quiet/use data */
           png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
           png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
                             PNG_FLAG_CRC_CRITICAL_IGNORE;
           break;
  
        case PNG_CRC_WARN_DISCARD:    /* Not a valid action for critical data */
           png_warning(png_ptr,
              "Can't discard critical data on CRC error");
        case PNG_CRC_ERROR_QUIT:                                /* Error/quit */
  
        case PNG_CRC_DEFAULT:
        default:
           png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
           break;
     }
  
     /* Tell libpng how we react to CRC errors in ancillary chunks */
     switch (ancil_action)
     {
        case PNG_CRC_NO_CHANGE:                       /* Leave setting as is */
           break;
  
        case PNG_CRC_WARN_USE:                              /* Warn/use data */
           png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
           png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
           break;
  
        case PNG_CRC_QUIET_USE:                            /* Quiet/use data */
           png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
           png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
                             PNG_FLAG_CRC_ANCILLARY_NOWARN;
           break;
  
        case PNG_CRC_ERROR_QUIT:                               /* Error/quit */
           png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
           png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
           break;
  
        case PNG_CRC_WARN_DISCARD:                      /* Warn/discard data */
  
        case PNG_CRC_DEFAULT:
        default:
           png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
           break;
     }
  }
  
  #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
      defined(PNG_FLOATING_POINT_SUPPORTED)
  /* Handle alpha and tRNS via a background color */
  void PNGAPI
  png_set_background(png_structp png_ptr,
     png_color_16p background_color, int background_gamma_code,
     int need_expand, double background_gamma)
  {
     png_debug(1, "in png_set_background");
  
     if (png_ptr == NULL)
        return;
     if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
     {
        png_warning(png_ptr, "Application must supply a known background gamma");
        return;
     }
  
     png_ptr->transformations |= PNG_BACKGROUND;
     png_memcpy(&(png_ptr->background), background_color,
        png_sizeof(png_color_16));
     png_ptr->background_gamma = (float)background_gamma;
     png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
     png_ptr->transformations |= (need_expand ? PNG_BACKGROUND_EXPAND : 0);
  }
  #endif
  
  #ifdef PNG_READ_16_TO_8_SUPPORTED
  /* Strip 16 bit depth files to 8 bit depth */
  void PNGAPI
  png_set_strip_16(png_structp png_ptr)
  {
     png_debug(1, "in png_set_strip_16");
  
     if (png_ptr == NULL)
        return;
     png_ptr->transformations |= PNG_16_TO_8;
  }
  #endif
  
  #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
  void PNGAPI
  png_set_strip_alpha(png_structp png_ptr)
  {
     png_debug(1, "in png_set_strip_alpha");
  
     if (png_ptr == NULL)
        return;
     png_ptr->flags |= PNG_FLAG_STRIP_ALPHA;
  }
  #endif
  
  #ifdef PNG_READ_QUANTIZE_SUPPORTED
  /* Quantize file to 8 bit.  Supply a palette, the current number
   * of elements in the palette, the maximum number of elements
   * allowed, and a histogram if possible.  If the current number
   * of colors is greater then the maximum number, the palette will be
   * modified to fit in the maximum number.  "full_quantize" indicates
   * whether we need a quantizeing cube set up for RGB images, or if we
   * simply are reducing the number of colors in a paletted image.
   */
  
  typedef struct png_dsort_struct
  {
     struct png_dsort_struct FAR * next;
     png_byte left;
     png_byte right;
  } png_dsort;
  typedef png_dsort FAR *       png_dsortp;
  typedef png_dsort FAR * FAR * png_dsortpp;
  
  void PNGAPI
  png_set_quantize(png_structp png_ptr, png_colorp palette,
     int num_palette, int maximum_colors, png_uint_16p histogram,
     int full_quantize)
  {
     png_debug(1, "in png_set_quantize");
  
     if (png_ptr == NULL)
        return;
     png_ptr->transformations |= PNG_QUANTIZE;
  
     if (!full_quantize)
     {
        int i;
  
        png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
           (png_uint_32)(num_palette * png_sizeof(png_byte)));
        for (i = 0; i < num_palette; i++)
           png_ptr->quantize_index[i] = (png_byte)i;
     }
  
     if (num_palette > maximum_colors)
     {
        if (histogram != NULL)
        {
           /* This is easy enough, just throw out the least used colors.
            * Perhaps not the best solution, but good enough.
            */
  
           int i;
  
           /* Initialize an array to sort colors */
           png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
              (png_uint_32)(num_palette * png_sizeof(png_byte)));
  
           /* Initialize the quantize_sort array */
           for (i = 0; i < num_palette; i++)
              png_ptr->quantize_sort[i] = (png_byte)i;
  
           /* Find the least used palette entries by starting a
            * bubble sort, and running it until we have sorted
            * out enough colors.  Note that we don't care about
            * sorting all the colors, just finding which are
            * least used.
            */
  
           for (i = num_palette - 1; i >= maximum_colors; i--)
           {
              int done; /* To stop early if the list is pre-sorted */
              int j;
  
              done = 1;
              for (j = 0; j < i; j++)
              {
                 if (histogram[png_ptr->quantize_sort[j]]
                     < histogram[png_ptr->quantize_sort[j + 1]])
                 {
                    png_byte t;
  
                    t = png_ptr->quantize_sort[j];
                    png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
                    png_ptr->quantize_sort[j + 1] = t;
                    done = 0;
                 }
              }
              if (done)
                 break;
           }
  
           /* Swap the palette around, and set up a table, if necessary */
           if (full_quantize)
           {
              int j = num_palette;
  
              /* Put all the useful colors within the max, but don't
               * move the others.
               */
              for (i = 0; i < maximum_colors; i++)
              {
                 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
                 {
                    do
                       j--;
                    while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
                    palette[i] = palette[j];
                 }
              }
           }
           else
           {
              int j = num_palette;
  
              /* Move all the used colors inside the max limit, and
               * develop a translation table.
               */
              for (i = 0; i < maximum_colors; i++)
              {
                 /* Only move the colors we need to */
                 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
                 {
                    png_color tmp_color;
  
                    do
                       j--;
                    while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
  
                    tmp_color = palette[j];
                    palette[j] = palette[i];
                    palette[i] = tmp_color;
                    /* Indicate where the color went */
                    png_ptr->quantize_index[j] = (png_byte)i;
                    png_ptr->quantize_index[i] = (png_byte)j;
                 }
              }
  
              /* Find closest color for those colors we are not using */
              for (i = 0; i < num_palette; i++)
              {
                 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
                 {
                    int min_d, k, min_k, d_index;
  
                    /* Find the closest color to one we threw out */
                    d_index = png_ptr->quantize_index[i];
                    min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
                    for (k = 1, min_k = 0; k < maximum_colors; k++)
                    {
                       int d;
  
                       d = PNG_COLOR_DIST(palette[d_index], palette[k]);
  
                       if (d < min_d)
                       {
                          min_d = d;
                          min_k = k;
                       }
                    }
                    /* Point to closest color */
                    png_ptr->quantize_index[i] = (png_byte)min_k;
                 }
              }
           }
           png_free(png_ptr, png_ptr->quantize_sort);
           png_ptr->quantize_sort = NULL;
        }
        else
        {
           /* This is much harder to do simply (and quickly).  Perhaps
            * we need to go through a median cut routine, but those
            * don't always behave themselves with only a few colors
            * as input.  So we will just find the closest two colors,
            * and throw out one of them (chosen somewhat randomly).
            * [We don't understand this at all, so if someone wants to
            *  work on improving it, be our guest - AED, GRP]
            */
           int i;
           int max_d;
           int num_new_palette;
           png_dsortp t;
           png_dsortpp hash;
  
           t = NULL;
  
           /* Initialize palette index arrays */
           png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
              (png_uint_32)(num_palette * png_sizeof(png_byte)));
           png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
              (png_uint_32)(num_palette * png_sizeof(png_byte)));
  
           /* Initialize the sort array */
           for (i = 0; i < num_palette; i++)
           {
              png_ptr->index_to_palette[i] = (png_byte)i;
              png_ptr->palette_to_index[i] = (png_byte)i;
           }
  
           hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
              png_sizeof(png_dsortp)));
  
           num_new_palette = num_palette;
  
           /* Initial wild guess at how far apart the farthest pixel
            * pair we will be eliminating will be.  Larger
            * numbers mean more areas will be allocated, Smaller
            * numbers run the risk of not saving enough data, and
            * having to do this all over again.
            *
            * I have not done extensive checking on this number.
            */
           max_d = 96;
  
           while (num_new_palette > maximum_colors)
           {
              for (i = 0; i < num_new_palette - 1; i++)
              {
                 int j;
  
                 for (j = i + 1; j < num_new_palette; j++)
                 {
                    int d;
  
                    d = PNG_COLOR_DIST(palette[i], palette[j]);
  
                    if (d <= max_d)
                    {
  
                       t = (png_dsortp)png_malloc_warn(png_ptr,
                           (png_uint_32)(png_sizeof(png_dsort)));
                       if (t == NULL)
                           break;
                       t->next = hash[d];
                       t->left = (png_byte)i;
                       t->right = (png_byte)j;
                       hash[d] = t;
                    }
                 }
                 if (t == NULL)
                    break;
              }
  
              if (t != NULL)
              for (i = 0; i <= max_d; i++)
              {
                 if (hash[i] != NULL)
                 {
                    png_dsortp p;
  
                    for (p = hash[i]; p; p = p->next)
                    {
                       if ((int)png_ptr->index_to_palette[p->left]
                          < num_new_palette &&
                          (int)png_ptr->index_to_palette[p->right]
                          < num_new_palette)
                       {
                          int j, next_j;
  
                          if (num_new_palette & 0x01)
                          {
                             j = p->left;
                             next_j = p->right;
                          }
                          else
                          {
                             j = p->right;
                             next_j = p->left;
                          }
  
                          num_new_palette--;
                          palette[png_ptr->index_to_palette[j]]
                            = palette[num_new_palette];
                          if (!full_quantize)
                          {
                             int k;
  
                             for (k = 0; k < num_palette; k++)
                             {
                                if (png_ptr->quantize_index[k] ==
                                   png_ptr->index_to_palette[j])
                                   png_ptr->quantize_index[k] =
                                      png_ptr->index_to_palette[next_j];
                                if ((int)png_ptr->quantize_index[k] ==
                                   num_new_palette)
                                   png_ptr->quantize_index[k] =
                                      png_ptr->index_to_palette[j];
                             }
                          }
  
                          png_ptr->index_to_palette[png_ptr->palette_to_index
                             [num_new_palette]] = png_ptr->index_to_palette[j];
                          png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
                             = png_ptr->palette_to_index[num_new_palette];
  
                          png_ptr->index_to_palette[j] =
                              (png_byte)num_new_palette;
                          png_ptr->palette_to_index[num_new_palette] =
                              (png_byte)j;
                       }
                       if (num_new_palette <= maximum_colors)
                          break;
                    }
                    if (num_new_palette <= maximum_colors)
                       break;
                 }
              }
  
              for (i = 0; i < 769; i++)
              {
                 if (hash[i] != NULL)
                 {
                    png_dsortp p = hash[i];
                    while (p)
                    {
                       t = p->next;
                       png_free(png_ptr, p);
                       p = t;
                    }
                 }
                 hash[i] = 0;
              }
              max_d += 96;
           }
           png_free(png_ptr, hash);
           png_free(png_ptr, png_ptr->palette_to_index);
           png_free(png_ptr, png_ptr->index_to_palette);
           png_ptr->palette_to_index = NULL;
           png_ptr->index_to_palette = NULL;
        }
        num_palette = maximum_colors;
     }
     if (png_ptr->palette == NULL)
     {
        png_ptr->palette = palette;
     }
     png_ptr->num_palette = (png_uint_16)num_palette;
  
     if (full_quantize)
     {
        int i;
        png_bytep distance;
        int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
           PNG_QUANTIZE_BLUE_BITS;
        int num_red = (1 << PNG_QUANTIZE_RED_BITS);
        int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
        int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
        png_size_t num_entries = ((png_size_t)1 << total_bits);
  
        png_ptr->palette_lookup = (png_bytep )png_calloc(png_ptr,
           (png_uint_32)(num_entries * png_sizeof(png_byte)));
  
        distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
           png_sizeof(png_byte)));
        png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
  
        for (i = 0; i < num_palette; i++)
        {
           int ir, ig, ib;
           int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
           int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
           int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
  
           for (ir = 0; ir < num_red; ir++)
           {
              /* int dr = abs(ir - r); */
              int dr = ((ir > r) ? ir - r : r - ir);
              int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
                  PNG_QUANTIZE_GREEN_BITS));
  
              for (ig = 0; ig < num_green; ig++)
              {
                 /* int dg = abs(ig - g); */
                 int dg = ((ig > g) ? ig - g : g - ig);
                 int dt = dr + dg;
                 int dm = ((dr > dg) ? dr : dg);
                 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
  
                 for (ib = 0; ib < num_blue; ib++)
                 {
                    int d_index = index_g | ib;
                    /* int db = abs(ib - b); */
                    int db = ((ib > b) ? ib - b : b - ib);
                    int dmax = ((dm > db) ? dm : db);
                    int d = dmax + dt + db;
  
                    if (d < (int)distance[d_index])
                    {
                       distance[d_index] = (png_byte)d;
                       png_ptr->palette_lookup[d_index] = (png_byte)i;
                    }
                 }
              }
           }
        }
  
        png_free(png_ptr, distance);
     }
  }
  #endif /* PNG_READ_QUANTIZE_SUPPORTED */
  
  #if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
  /* Transform the image from the file_gamma to the screen_gamma.  We
   * only do transformations on images where the file_gamma and screen_gamma
   * are not close reciprocals, otherwise it slows things down slightly, and
   * also needlessly introduces small errors.
   *
   * We will turn off gamma transformation later if no semitransparent entries
   * are present in the tRNS array for palette images.  We can't do it here
   * because we don't necessarily have the tRNS chunk yet.
   */
  void PNGAPI
  png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
  {
     png_debug(1, "in png_set_gamma");
  
     if (png_ptr == NULL)
        return;
  
     if ((fabs(scrn_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD) ||
         (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) ||
         (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
       png_ptr->transformations |= PNG_GAMMA;
     png_ptr->gamma = (float)file_gamma;
     png_ptr->screen_gamma = (float)scrn_gamma;
  }
  #endif
  
  #ifdef PNG_READ_EXPAND_SUPPORTED
  /* Expand paletted images to RGB, expand grayscale images of
   * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
   * to alpha channels.
   */
  void PNGAPI
  png_set_expand(png_structp png_ptr)
  {
     png_debug(1, "in png_set_expand");
  
     if (png_ptr == NULL)
        return;
  
     png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
  }
  
  /* GRR 19990627:  the following three functions currently are identical
   *  to png_set_expand().  However, it is entirely reasonable that someone
   *  might wish to expand an indexed image to RGB but *not* expand a single,
   *  fully transparent palette entry to a full alpha channel--perhaps instead
   *  convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
   *  the transparent color with a particular RGB value, or drop tRNS entirely.
   *  IOW, a future version of the library may make the transformations flag
   *  a bit more fine-grained, with separate bits for each of these three
   *  functions.
   *
   *  More to the point, these functions make it obvious what libpng will be
   *  doing, whereas "expand" can (and does) mean any number of things.
   *
   *  GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
   *  to expand only the sample depth but not to expand the tRNS to alpha
   *  and its name was changed to png_set_expand_gray_1_2_4_to_8().
   */
  
  /* Expand paletted images to RGB. */
  void PNGAPI
  png_set_palette_to_rgb(png_structp png_ptr)
  {
     png_debug(1, "in png_set_palette_to_rgb");
  
     if (png_ptr == NULL)
        return;
  
     png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
  }
  
  /* Expand grayscale images of less than 8-bit depth to 8 bits. */
  void PNGAPI
  png_set_expand_gray_1_2_4_to_8(png_structp png_ptr)
  {
     png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
  
     if (png_ptr == NULL)
        return;
  
     png_ptr->transformations |= PNG_EXPAND;
     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
  }
  
  
  
  /* Expand tRNS chunks to alpha channels. */
  void PNGAPI
  png_set_tRNS_to_alpha(png_structp png_ptr)
  {
     png_debug(1, "in png_set_tRNS_to_alpha");
  
     png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
  }
  #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
  void PNGAPI
  png_set_gray_to_rgb(png_structp png_ptr)
  {
     png_debug(1, "in png_set_gray_to_rgb");
  
     png_ptr->transformations |= PNG_GRAY_TO_RGB;
     png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
  }
  #endif
  
  #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
  #ifdef PNG_FLOATING_POINT_SUPPORTED
  /* Convert a RGB image to a grayscale of the same width.  This allows us,
   * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
   */
  
  void PNGAPI
  png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
     double green)
  {
     int red_fixed = (int)((float)red*100000.0 + 0.5);
     int green_fixed = (int)((float)green*100000.0 + 0.5);
     if (png_ptr == NULL)
        return;
     png_set_rgb_to_gray_fixed(png_ptr, error_action, red_fixed, green_fixed);
  }
  #endif
  
  void PNGAPI
  png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
     png_fixed_point red, png_fixed_point green)
  {
     png_debug(1, "in png_set_rgb_to_gray");
  
     if (png_ptr == NULL)
        return;
  
     switch(error_action)
     {
        case 1: png_ptr->transformations |= PNG_RGB_TO_GRAY;
                break;
  
        case 2: png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
                break;
  
        case 3: png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
           break;
  
        default:
           png_error(png_ptr, "invalid error action in png_set_rgb_to_gray");
           break;
     }
     if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
  #ifdef PNG_READ_EXPAND_SUPPORTED
        png_ptr->transformations |= PNG_EXPAND;
  #else
     {
        png_warning(png_ptr,
          "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
        png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
     }
  #endif
     {
        png_uint_16 red_int, green_int;
        if (red < 0 || green < 0)
        {
           red_int   =  6968; /* .212671 * 32768 + .5 */
           green_int = 23434; /* .715160 * 32768 + .5 */
        }
        else if (red + green < 100000L)
        {
           red_int = (png_uint_16)(((png_uint_32)red*32768L)/100000L);
           green_int = (png_uint_16)(((png_uint_32)green*32768L)/100000L);
        }
        else
        {
           png_warning(png_ptr, "ignoring out of range rgb_to_gray coefficients");
           red_int   =  6968;
           green_int = 23434;
        }
        png_ptr->rgb_to_gray_red_coeff   = red_int;
        png_ptr->rgb_to_gray_green_coeff = green_int;
        png_ptr->rgb_to_gray_blue_coeff  =
           (png_uint_16)(32768 - red_int - green_int);
     }
  }
  #endif
  
  #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
      defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  void PNGAPI
  png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
     read_user_transform_fn)
  {
     png_debug(1, "in png_set_read_user_transform_fn");
  
     if (png_ptr == NULL)
        return;
  
  #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
     png_ptr->transformations |= PNG_USER_TRANSFORM;
     png_ptr->read_user_transform_fn = read_user_transform_fn;
  #endif
  }
  #endif
  
  /* Initialize everything needed for the read.  This includes modifying
   * the palette.
   */
  void /* PRIVATE */
  png_init_read_transformations(png_structp png_ptr)
  {
     png_debug(1, "in png_init_read_transformations");
  
    {
  #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
      defined(PNG_READ_SHIFT_SUPPORTED) || \
      defined(PNG_READ_GAMMA_SUPPORTED)
     int color_type = png_ptr->color_type;
  #endif
  
  #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
     /* Detect gray background and attempt to enable optimization
      * for gray --> RGB case
      *
      * Note:  if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
      * RGB_ALPHA (in which case need_expand is superfluous anyway), the
      * background color might actually be gray yet not be flagged as such.
      * This is not a problem for the current code, which uses
      * PNG_BACKGROUND_IS_GRAY only to decide when to do the
      * png_do_gray_to_rgb() transformation.
      */
     if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
         !(color_type & PNG_COLOR_MASK_COLOR))
     {
            png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
     } else if ((png_ptr->transformations & PNG_BACKGROUND) &&
                !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
                (png_ptr->transformations & PNG_GRAY_TO_RGB) &&
                png_ptr->background.red == png_ptr->background.green &&
                png_ptr->background.red == png_ptr->background.blue)
     {
            png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
            png_ptr->background.gray = png_ptr->background.red;
     }
  #endif
  
     if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
         (png_ptr->transformations & PNG_EXPAND))
     {
        if (!(color_type & PNG_COLOR_MASK_COLOR))  /* i.e., GRAY or GRAY_ALPHA */
        {
           /* Expand background and tRNS chunks */
           switch (png_ptr->bit_depth)
           {
              case 1:
                 png_ptr->background.gray *= (png_uint_16)0xff;
                 png_ptr->background.red = png_ptr->background.green
                   =  png_ptr->background.blue = png_ptr->background.gray;
                 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
                 {
                   png_ptr->trans_color.gray *= (png_uint_16)0xff;
                   png_ptr->trans_color.red = png_ptr->trans_color.green
                     = png_ptr->trans_color.blue = png_ptr->trans_color.gray;
                 }
                 break;
  
              case 2:
                 png_ptr->background.gray *= (png_uint_16)0x55;
                 png_ptr->background.red = png_ptr->background.green
                   = png_ptr->background.blue = png_ptr->background.gray;
                 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
                 {
                   png_ptr->trans_color.gray *= (png_uint_16)0x55;
                   png_ptr->trans_color.red = png_ptr->trans_color.green
                     = png_ptr->trans_color.blue = png_ptr->trans_color.gray;
                 }
                 break;
  
              case 4:
                 png_ptr->background.gray *= (png_uint_16)0x11;
                 png_ptr->background.red = png_ptr->background.green
                   = png_ptr->background.blue = png_ptr->background.gray;
                 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
                 {
                   png_ptr->trans_color.gray *= (png_uint_16)0x11;
                   png_ptr->trans_color.red = png_ptr->trans_color.green
                     = png_ptr->trans_color.blue = png_ptr->trans_color.gray;
                 }
                 break;
  
              default:
  
              case 8:
  
              case 16:
                 png_ptr->background.red = png_ptr->background.green
                   = png_ptr->background.blue = png_ptr->background.gray;
                 break;
           }
        }
        else if (color_type == PNG_COLOR_TYPE_PALETTE)
        {
           png_ptr->background.red   =
              png_ptr->palette[png_ptr->background.index].red;
           png_ptr->background.green =
              png_ptr->palette[png_ptr->background.index].green;
           png_ptr->background.blue  =
              png_ptr->palette[png_ptr->background.index].blue;
  
  #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
          if (png_ptr->transformations & PNG_INVERT_ALPHA)
          {
  #ifdef PNG_READ_EXPAND_SUPPORTED
             if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
  #endif
             {
             /* Invert the alpha channel (in tRNS) unless the pixels are
              * going to be expanded, in which case leave it for later
              */
                int i, istop;
                istop=(int)png_ptr->num_trans;
                for (i=0; i<istop; i++)
                   png_ptr->trans_alpha[i] = (png_byte)(255 - png_ptr->trans_alpha[i]);
             }
          }
  #endif
  
        }
     }
  #endif
  
  #if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
     png_ptr->background_1 = png_ptr->background;
  #endif
  #if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
  
     if ((color_type == PNG_COLOR_TYPE_PALETTE && png_ptr->num_trans != 0)
         && (fabs(png_ptr->screen_gamma * png_ptr->gamma - 1.0)
           < PNG_GAMMA_THRESHOLD))
     {
      int i, k;
      k=0;
      for (i=0; i<png_ptr->num_trans; i++)
      {
        if (png_ptr->trans_alpha[i] != 0 && png_ptr->trans_alpha[i] != 0xff)
          k=1; /* Partial transparency is present */
      }
      if (k == 0)
        png_ptr->transformations &= ~PNG_GAMMA;
     }
  
     if ((png_ptr->transformations & (PNG_GAMMA | PNG_RGB_TO_GRAY)) &&
          png_ptr->gamma != 0.0)
     {
        png_build_gamma_table(png_ptr, png_ptr->bit_depth);
  
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
        if (png_ptr->transformations & PNG_BACKGROUND)
        {
           if (color_type == PNG_COLOR_TYPE_PALETTE)
           {
             /* Could skip if no transparency */
              png_color back, back_1;
              png_colorp palette = png_ptr->palette;
              int num_palette = png_ptr->num_palette;
              int i;
              if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
              {
                 back.red = png_ptr->gamma_table[png_ptr->background.red];
                 back.green = png_ptr->gamma_table[png_ptr->background.green];
                 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
  
                 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
                 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
                 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
              }
              else
              {
                 double g, gs;
  
                 switch (png_ptr->background_gamma_type)
                 {
                    case PNG_BACKGROUND_GAMMA_SCREEN:
                       g = (png_ptr->screen_gamma);
                       gs = 1.0;
                       break;
  
                    case PNG_BACKGROUND_GAMMA_FILE:
                       g = 1.0 / (png_ptr->gamma);
                       gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
                       break;
  
                    case PNG_BACKGROUND_GAMMA_UNIQUE:
                       g = 1.0 / (png_ptr->background_gamma);
                       gs = 1.0 / (png_ptr->background_gamma *
                                   png_ptr->screen_gamma);
                       break;
                    default:
                       g = 1.0;    /* back_1 */
                       gs = 1.0;   /* back */
                 }
  
                 if ( fabs(gs - 1.0) < PNG_GAMMA_THRESHOLD)
                 {
                    back.red   = (png_byte)png_ptr->background.red;
                    back.green = (png_byte)png_ptr->background.green;
                    back.blue  = (png_byte)png_ptr->background.blue;
                 }
                 else
                 {
                    back.red = (png_byte)(pow(
                       (double)png_ptr->background.red/255.0, gs) * 255.0 + .5);
                    back.green = (png_byte)(pow(
                       (double)png_ptr->background.green/255.0, gs) * 255.0
                           + .5);
                    back.blue = (png_byte)(pow(
                       (double)png_ptr->background.blue/255.0, gs) * 255.0 + .5);
                 }
  
                 back_1.red = (png_byte)(pow(
                    (double)png_ptr->background.red/255.0, g) * 255.0 + .5);
                 back_1.green = (png_byte)(pow(
                    (double)png_ptr->background.green/255.0, g) * 255.0 + .5);
                 back_1.blue = (png_byte)(pow(
                    (double)png_ptr->background.blue/255.0, g) * 255.0 + .5);
              }
              for (i = 0; i < num_palette; i++)
              {
                 if (i < (int)png_ptr->num_trans && png_ptr->trans_alpha[i] != 0xff)
                 {
                    if (png_ptr->trans_alpha[i] == 0)
                    {
                       palette[i] = back;
                    }
                    else /* if (png_ptr->trans_alpha[i] != 0xff) */
                    {
                       png_byte v, w;
  
                       v = png_ptr->gamma_to_1[palette[i].red];
                       png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
                       palette[i].red = png_ptr->gamma_from_1[w];
  
                       v = png_ptr->gamma_to_1[palette[i].green];
                       png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
                       palette[i].green = png_ptr->gamma_from_1[w];
  
                       v = png_ptr->gamma_to_1[palette[i].blue];
                       png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
                       palette[i].blue = png_ptr->gamma_from_1[w];
                    }
                 }
                 else
                 {
                    palette[i].red = png_ptr->gamma_table[palette[i].red];
                    palette[i].green = png_ptr->gamma_table[palette[i].green];
                    palette[i].blue = png_ptr->gamma_table[palette[i].blue];
                 }
              }
              /* Prevent the transformations being done again, and make sure
               * that the now spurious alpha channel is stripped - the code
               * has just reduced background composition and gamma correction
               * to a simple alpha channel strip.
               */
              png_ptr->transformations &= ~PNG_BACKGROUND;
              png_ptr->transformations &= ~PNG_GAMMA;
              png_ptr->transformations |= PNG_STRIP_ALPHA;
           }
           /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
           else
           /* color_type != PNG_COLOR_TYPE_PALETTE */
           {
              double m = (double)(((png_uint_32)1 << png_ptr->bit_depth) - 1);
              double g = 1.0;
              double gs = 1.0;
  
              switch (png_ptr->background_gamma_type)
              {
                 case PNG_BACKGROUND_GAMMA_SCREEN:
                    g = (png_ptr->screen_gamma);
                    gs = 1.0;
                    break;
  
                 case PNG_BACKGROUND_GAMMA_FILE:
                    g = 1.0 / (png_ptr->gamma);
                    gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
                    break;
  
                 case PNG_BACKGROUND_GAMMA_UNIQUE:
                    g = 1.0 / (png_ptr->background_gamma);
                    gs = 1.0 / (png_ptr->background_gamma *
                       png_ptr->screen_gamma);
                    break;
  
                 default:
                    png_error(png_ptr, "invalid background gamma type");
              }
  
              png_ptr->background_1.gray = (png_uint_16)(pow(
                 (double)png_ptr->background.gray / m, g) * m + .5);
              png_ptr->background.gray = (png_uint_16)(pow(
                 (double)png_ptr->background.gray / m, gs) * m + .5);
  
              if ((png_ptr->background.red != png_ptr->background.green) ||
                  (png_ptr->background.red != png_ptr->background.blue) ||
                  (png_ptr->background.red != png_ptr->background.gray))
              {
                 /* RGB or RGBA with color background */
                 png_ptr->background_1.red = (png_uint_16)(pow(
                    (double)png_ptr->background.red / m, g) * m + .5);
                 png_ptr->background_1.green = (png_uint_16)(pow(
                    (double)png_ptr->background.green / m, g) * m + .5);
                 png_ptr->background_1.blue = (png_uint_16)(pow(
                    (double)png_ptr->background.blue / m, g) * m + .5);
                 png_ptr->background.red = (png_uint_16)(pow(
                    (double)png_ptr->background.red / m, gs) * m + .5);
                 png_ptr->background.green = (png_uint_16)(pow(
                    (double)png_ptr->background.green / m, gs) * m + .5);
                 png_ptr->background.blue = (png_uint_16)(pow(
                    (double)png_ptr->background.blue / m, gs) * m + .5);
              }
              else
              {
                 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
                 png_ptr->background_1.red = png_ptr->background_1.green
                   = png_ptr->background_1.blue = png_ptr->background_1.gray;
                 png_ptr->background.red = png_ptr->background.green
                   = png_ptr->background.blue = png_ptr->background.gray;
              }
           }
        }
        else
        /* Transformation does not include PNG_BACKGROUND */
  #endif /* PNG_READ_BACKGROUND_SUPPORTED */
        if (color_type == PNG_COLOR_TYPE_PALETTE)
        {
           png_colorp palette = png_ptr->palette;
           int num_palette = png_ptr->num_palette;
           int i;
  
           for (i = 0; i < num_palette; i++)
           {
              palette[i].red = png_ptr->gamma_table[palette[i].red];
              palette[i].green = png_ptr->gamma_table[palette[i].green];
              palette[i].blue = png_ptr->gamma_table[palette[i].blue];
           }
  
           /* Done the gamma correction. */
           png_ptr->transformations &= ~PNG_GAMMA;
        }
     }
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
     else
  #endif
  #endif /* PNG_READ_GAMMA_SUPPORTED && PNG_FLOATING_POINT_SUPPORTED */
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
     /* No GAMMA transformation */
     if ((png_ptr->transformations & PNG_BACKGROUND) &&
         (color_type == PNG_COLOR_TYPE_PALETTE))
     {
        int i;
        int istop = (int)png_ptr->num_trans;
        png_color back;
        png_colorp palette = png_ptr->palette;
  
        back.red   = (png_byte)png_ptr->background.red;
        back.green = (png_byte)png_ptr->background.green;
        back.blue  = (png_byte)png_ptr->background.blue;
  
        for (i = 0; i < istop; i++)
        {
           if (png_ptr->trans_alpha[i] == 0)
           {
              palette[i] = back;
           }
           else if (png_ptr->trans_alpha[i] != 0xff)
           {
              /* The png_composite() macro is defined in png.h */
              png_composite(palette[i].red, palette[i].red,
                 png_ptr->trans_alpha[i], back.red);
              png_composite(palette[i].green, palette[i].green,
                 png_ptr->trans_alpha[i], back.green);
              png_composite(palette[i].blue, palette[i].blue,
                 png_ptr->trans_alpha[i], back.blue);
           }
        }
  
        /* Handled alpha, still need to strip the channel. */
        png_ptr->transformations &= ~PNG_BACKGROUND;
        png_ptr->transformations |= PNG_STRIP_ALPHA;
     }
  #endif /* PNG_READ_BACKGROUND_SUPPORTED */
  
  #ifdef PNG_READ_SHIFT_SUPPORTED
     if ((png_ptr->transformations & PNG_SHIFT) &&
        (color_type == PNG_COLOR_TYPE_PALETTE))
     {
        png_uint_16 i;
        png_uint_16 istop = png_ptr->num_palette;
        int sr = 8 - png_ptr->sig_bit.red;
        int sg = 8 - png_ptr->sig_bit.green;
        int sb = 8 - png_ptr->sig_bit.blue;
  
        if (sr < 0 || sr > 8)
           sr = 0;
        if (sg < 0 || sg > 8)
           sg = 0;
        if (sb < 0 || sb > 8)
           sb = 0;
        for (i = 0; i < istop; i++)
        {
           png_ptr->palette[i].red >>= sr;
           png_ptr->palette[i].green >>= sg;
           png_ptr->palette[i].blue >>= sb;
        }
     }
  #endif  /* PNG_READ_SHIFT_SUPPORTED */
   }
  #if !defined(PNG_READ_GAMMA_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) \
   && !defined(PNG_READ_BACKGROUND_SUPPORTED)
     if (png_ptr)
        return;
  #endif
  }
  
  /* Modify the info structure to reflect the transformations.  The
   * info should be updated so a PNG file could be written with it,
   * assuming the transformations result in valid PNG data.
   */
  void /* PRIVATE */
  png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
  {
     png_debug(1, "in png_read_transform_info");
  
  #ifdef PNG_READ_EXPAND_SUPPORTED
     if (png_ptr->transformations & PNG_EXPAND)
     {
        if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
        {
           if (png_ptr->num_trans &&
                (png_ptr->transformations & PNG_EXPAND_tRNS))
              info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
           else
              info_ptr->color_type = PNG_COLOR_TYPE_RGB;
           info_ptr->bit_depth = 8;
           info_ptr->num_trans = 0;
        }
        else
        {
           if (png_ptr->num_trans)
           {
              if (png_ptr->transformations & PNG_EXPAND_tRNS)
                info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
           }
           if (info_ptr->bit_depth < 8)
              info_ptr->bit_depth = 8;
           info_ptr->num_trans = 0;
        }
     }
  #endif
  
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
     if (png_ptr->transformations & PNG_BACKGROUND)
     {
        info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA;
        info_ptr->num_trans = 0;
        info_ptr->background = png_ptr->background;
     }
  #endif
  
  #ifdef PNG_READ_GAMMA_SUPPORTED
     if (png_ptr->transformations & PNG_GAMMA)
     {
  #ifdef PNG_FLOATING_POINT_SUPPORTED
        info_ptr->gamma = png_ptr->gamma;
  #endif
  #ifdef PNG_FIXED_POINT_SUPPORTED
        info_ptr->int_gamma = png_ptr->int_gamma;
  #endif
     }
  #endif
  
  #ifdef PNG_READ_16_TO_8_SUPPORTED
     if ((png_ptr->transformations & PNG_16_TO_8) && (info_ptr->bit_depth == 16))
        info_ptr->bit_depth = 8;
  #endif
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
     if (png_ptr->transformations & PNG_GRAY_TO_RGB)
        info_ptr->color_type |= PNG_COLOR_MASK_COLOR;
  #endif
  
  #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
     if (png_ptr->transformations & PNG_RGB_TO_GRAY)
        info_ptr->color_type &= ~PNG_COLOR_MASK_COLOR;
  #endif
  
  #ifdef PNG_READ_QUANTIZE_SUPPORTED
     if (png_ptr->transformations & PNG_QUANTIZE)
     {
        if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
            (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
            png_ptr->palette_lookup && info_ptr->bit_depth == 8)
        {
           info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
        }
     }
  #endif
  
  #ifdef PNG_READ_PACK_SUPPORTED
     if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
        info_ptr->bit_depth = 8;
  #endif
  
     if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
        info_ptr->channels = 1;
     else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
        info_ptr->channels = 3;
     else
        info_ptr->channels = 1;
  
  #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
     if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
        info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA;
  #endif
  
     if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
        info_ptr->channels++;
  
  #ifdef PNG_READ_FILLER_SUPPORTED
     /* STRIP_ALPHA and FILLER allowed:  MASK_ALPHA bit stripped above */
     if ((png_ptr->transformations & PNG_FILLER) &&
         ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
         (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
     {
        info_ptr->channels++;
        /* If adding a true alpha channel not just filler */
        if (png_ptr->transformations & PNG_ADD_ALPHA)
          info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
     }
  #endif
  
  #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
  defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
     if (png_ptr->transformations & PNG_USER_TRANSFORM)
       {
         if (info_ptr->bit_depth < png_ptr->user_transform_depth)
           info_ptr->bit_depth = png_ptr->user_transform_depth;
         if (info_ptr->channels < png_ptr->user_transform_channels)
           info_ptr->channels = png_ptr->user_transform_channels;
       }
  #endif
  
     info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
        info_ptr->bit_depth);
  
     info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
  
  #ifndef PNG_READ_EXPAND_SUPPORTED
     if (png_ptr)
        return;
  #endif
  }
  
  /* Transform the row.  The order of transformations is significant,
   * and is very touchy.  If you add a transformation, take care to
   * decide how it fits in with the other transformations here.
   */
  void /* PRIVATE */
  png_do_read_transformations(png_structp png_ptr)
  {
     png_debug(1, "in png_do_read_transformations");
  
     if (png_ptr->row_buf == NULL)
     {
  #ifdef PNG_STDIO_SUPPORTED
        char msg[50];
  
        png_snprintf2(msg, 50,
           "NULL row buffer for row %ld, pass %d", (long)png_ptr->row_number,
           png_ptr->pass);
        png_error(png_ptr, msg);
  #else
        png_error(png_ptr, "NULL row buffer");
  #endif
     }
  #ifdef PNG_WARN_UNINITIALIZED_ROW
     if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
        /* Application has failed to call either png_read_start_image()
         * or png_read_update_info() after setting transforms that expand
         * pixels.  This check added to libpng-1.2.19
         */
  #if (PNG_WARN_UNINITIALIZED_ROW==1)
        png_error(png_ptr, "Uninitialized row");
  #else
        png_warning(png_ptr, "Uninitialized row");
  #endif
  #endif
  
  #ifdef PNG_READ_EXPAND_SUPPORTED
     if (png_ptr->transformations & PNG_EXPAND)
     {
        if (png_ptr->row_info.color_type == PNG_COLOR_TYPE_PALETTE)
        {
           png_do_expand_palette(&(png_ptr->row_info), png_ptr->row_buf + 1,
              png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
        }
        else
        {
           if (png_ptr->num_trans &&
               (png_ptr->transformations & PNG_EXPAND_tRNS))
              png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
                 &(png_ptr->trans_color));
           else
              png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
                 NULL);
        }
     }
  #endif
  
  #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
     if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
        png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
           PNG_FLAG_FILLER_AFTER | (png_ptr->flags & PNG_FLAG_STRIP_ALPHA));
  #endif
  
  #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
     if (png_ptr->transformations & PNG_RGB_TO_GRAY)
     {
        int rgb_error =
           png_do_rgb_to_gray(png_ptr, &(png_ptr->row_info),
               png_ptr->row_buf + 1);
        if (rgb_error)
        {
           png_ptr->rgb_to_gray_status=1;
           if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
               PNG_RGB_TO_GRAY_WARN)
              png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
           if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
               PNG_RGB_TO_GRAY_ERR)
              png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
        }
     }
  #endif
  
  /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
   *
   *   In most cases, the "simple transparency" should be done prior to doing
   *   gray-to-RGB, or you will have to test 3x as many bytes to check if a
   *   pixel is transparent.  You would also need to make sure that the
   *   transparency information is upgraded to RGB.
   *
   *   To summarize, the current flow is:
   *   - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
   *                                   with background "in place" if transparent,
   *                                   convert to RGB if necessary
   *   - Gray + alpha -> composite with gray background and remove alpha bytes,
   *                                   convert to RGB if necessary
   *
   *   To support RGB backgrounds for gray images we need:
   *   - Gray + simple transparency -> convert to RGB + simple transparency,
   *                                   compare 3 or 6 bytes and composite with
   *                                   background "in place" if transparent
   *                                   (3x compare/pixel compared to doing
   *                                   composite with gray bkgrnd)
   *   - Gray + alpha -> convert to RGB + alpha, composite with background and
   *                                   remove alpha bytes (3x float
   *                                   operations/pixel compared with composite
   *                                   on gray background)
   *
   *  Greg's change will do this.  The reason it wasn't done before is for
   *  performance, as this increases the per-pixel operations.  If we would check
   *  in advance if the background was gray or RGB, and position the gray-to-RGB
   *  transform appropriately, then it would save a lot of work/time.
   */
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
     /* If gray -> RGB, do so now only if background is non-gray; else do later
      * for performance reasons
      */
     if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
         !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
        png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
     if ((png_ptr->transformations & PNG_BACKGROUND) &&
        ((png_ptr->num_trans != 0 ) ||
        (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)))
        png_do_background(&(png_ptr->row_info), png_ptr->row_buf + 1,
           &(png_ptr->trans_color), &(png_ptr->background)
  #ifdef PNG_READ_GAMMA_SUPPORTED
           , &(png_ptr->background_1),
           png_ptr->gamma_table, png_ptr->gamma_from_1,
           png_ptr->gamma_to_1, png_ptr->gamma_16_table,
           png_ptr->gamma_16_from_1, png_ptr->gamma_16_to_1,
           png_ptr->gamma_shift
  #endif
  );
  #endif
  
  #ifdef PNG_READ_GAMMA_SUPPORTED
     if ((png_ptr->transformations & PNG_GAMMA) &&
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
         !((png_ptr->transformations & PNG_BACKGROUND) &&
         ((png_ptr->num_trans != 0) ||
         (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
  #endif
         (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
        png_do_gamma(&(png_ptr->row_info), png_ptr->row_buf + 1,
            png_ptr->gamma_table, png_ptr->gamma_16_table,
            png_ptr->gamma_shift);
  #endif
  
  #ifdef PNG_READ_16_TO_8_SUPPORTED
     if (png_ptr->transformations & PNG_16_TO_8)
        png_do_chop(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_QUANTIZE_SUPPORTED
     if (png_ptr->transformations & PNG_QUANTIZE)
     {
        png_do_quantize((png_row_infop)&(png_ptr->row_info), png_ptr->row_buf + 1,
           png_ptr->palette_lookup, png_ptr->quantize_index);
        if (png_ptr->row_info.rowbytes == (png_uint_32)0)
           png_error(png_ptr, "png_do_quantize returned rowbytes=0");
     }
  #endif
  
  #ifdef PNG_READ_INVERT_SUPPORTED
     if (png_ptr->transformations & PNG_INVERT_MONO)
        png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_SHIFT_SUPPORTED
     if (png_ptr->transformations & PNG_SHIFT)
        png_do_unshift(&(png_ptr->row_info), png_ptr->row_buf + 1,
           &(png_ptr->shift));
  #endif
  
  #ifdef PNG_READ_PACK_SUPPORTED
     if (png_ptr->transformations & PNG_PACK)
        png_do_unpack(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_BGR_SUPPORTED
     if (png_ptr->transformations & PNG_BGR)
        png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_PACKSWAP_SUPPORTED
     if (png_ptr->transformations & PNG_PACKSWAP)
        png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
     /* If gray -> RGB, do so now only if we did not do so above */
     if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
         (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
        png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_FILLER_SUPPORTED
     if (png_ptr->transformations & PNG_FILLER)
        png_do_read_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
           (png_uint_32)png_ptr->filler, png_ptr->flags);
  #endif
  
  #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
     if (png_ptr->transformations & PNG_INVERT_ALPHA)
        png_do_read_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
     if (png_ptr->transformations & PNG_SWAP_ALPHA)
        png_do_read_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_SWAP_SUPPORTED
     if (png_ptr->transformations & PNG_SWAP_BYTES)
        png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
  #endif
  
  #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
     if (png_ptr->transformations & PNG_USER_TRANSFORM)
      {
        if (png_ptr->read_user_transform_fn != NULL)
           (*(png_ptr->read_user_transform_fn)) /* User read transform function */
              (png_ptr,                    /* png_ptr */
                 &(png_ptr->row_info),     /* row_info: */
                 /*  png_uint_32 width;       width of row */
                 /*  png_uint_32 rowbytes;    number of bytes in row */
                 /*  png_byte color_type;     color type of pixels */
                 /*  png_byte bit_depth;      bit depth of samples */
                 /*  png_byte channels;       number of channels (1-4) */
                 /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
                 png_ptr->row_buf + 1);    /* start of pixel data for row */
  #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
        if (png_ptr->user_transform_depth)
           png_ptr->row_info.bit_depth = png_ptr->user_transform_depth;
        if (png_ptr->user_transform_channels)
           png_ptr->row_info.channels = png_ptr->user_transform_channels;
  #endif
        png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
           png_ptr->row_info.channels);
        png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
           png_ptr->row_info.width);
     }
  #endif
  
  }
  
  #ifdef PNG_READ_PACK_SUPPORTED
  /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
   * without changing the actual values.  Thus, if you had a row with
   * a bit depth of 1, you would end up with bytes that only contained
   * the numbers 0 or 1.  If you would rather they contain 0 and 255, use
   * png_do_shift() after this.
   */
  void /* PRIVATE */
  png_do_unpack(png_row_infop row_info, png_bytep row)
  {
     png_debug(1, "in png_do_unpack");
  
     if (row_info->bit_depth < 8)
     {
        png_uint_32 i;
        png_uint_32 row_width=row_info->width;
  
        switch (row_info->bit_depth)
        {
           case 1:
           {
              png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
              png_bytep dp = row + (png_size_t)row_width - 1;
              png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
              for (i = 0; i < row_width; i++)
              {
                 *dp = (png_byte)((*sp >> shift) & 0x01);
                 if (shift == 7)
                 {
                    shift = 0;
                    sp--;
                 }
                 else
                    shift++;
  
                 dp--;
              }
              break;
           }
  
           case 2:
           {
  
              png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
              png_bytep dp = row + (png_size_t)row_width - 1;
              png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
              for (i = 0; i < row_width; i++)
              {
                 *dp = (png_byte)((*sp >> shift) & 0x03);
                 if (shift == 6)
                 {
                    shift = 0;
                    sp--;
                 }
                 else
                    shift += 2;
  
                 dp--;
              }
              break;
           }
  
           case 4:
           {
              png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
              png_bytep dp = row + (png_size_t)row_width - 1;
              png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
              for (i = 0; i < row_width; i++)
              {
                 *dp = (png_byte)((*sp >> shift) & 0x0f);
                 if (shift == 4)
                 {
                    shift = 0;
                    sp--;
                 }
                 else
                    shift = 4;
  
                 dp--;
              }
              break;
           }
  
           default:
              break;
        }
        row_info->bit_depth = 8;
        row_info->pixel_depth = (png_byte)(8 * row_info->channels);
        row_info->rowbytes = row_width * row_info->channels;
     }
  }
  #endif
  
  #ifdef PNG_READ_SHIFT_SUPPORTED
  /* Reverse the effects of png_do_shift.  This routine merely shifts the
   * pixels back to their significant bits values.  Thus, if you have
   * a row of bit depth 8, but only 5 are significant, this will shift
   * the values back to 0 through 31.
   */
  void /* PRIVATE */
  png_do_unshift(png_row_infop row_info, png_bytep row, png_color_8p sig_bits)
  {
     png_debug(1, "in png_do_unshift");
  
     if (
         row_info->color_type != PNG_COLOR_TYPE_PALETTE)
     {
        int shift[4];
        int channels = 0;
        int c;
        png_uint_16 value = 0;
        png_uint_32 row_width = row_info->width;
  
        if (row_info->color_type & PNG_COLOR_MASK_COLOR)
        {
           shift[channels++] = row_info->bit_depth - sig_bits->red;
           shift[channels++] = row_info->bit_depth - sig_bits->green;
           shift[channels++] = row_info->bit_depth - sig_bits->blue;
        }
        else
        {
           shift[channels++] = row_info->bit_depth - sig_bits->gray;
        }
        if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
        {
           shift[channels++] = row_info->bit_depth - sig_bits->alpha;
        }
  
        for (c = 0; c < channels; c++)
        {
           if (shift[c] <= 0)
              shift[c] = 0;
           else
              value = 1;
        }
  
        if (!value)
           return;
  
        switch (row_info->bit_depth)
        {
           default:
              break; 
  
           case 2:
           {
              png_bytep bp;
              png_uint_32 i;
              png_uint_32 istop = row_info->rowbytes;
  
              for (bp = row, i = 0; i < istop; i++)
              {
                 *bp >>= 1;
                 *bp++ &= 0x55;
              }
              break;
           }
  
           case 4:
           {
              png_bytep bp = row;
              png_uint_32 i;
              png_uint_32 istop = row_info->rowbytes;
              png_byte mask = (png_byte)((((int)0xf0 >> shift[0]) & (int)0xf0) |
                 (png_byte)((int)0xf >> shift[0]));
  
              for (i = 0; i < istop; i++)
              {
                 *bp >>= shift[0];
                 *bp++ &= mask;
              }
              break;
           }
  
           case 8:
           {
              png_bytep bp = row;
              png_uint_32 i;
              png_uint_32 istop = row_width * channels;
  
              for (i = 0; i < istop; i++)
              {
                 *bp++ >>= shift[i%channels];
              }
              break;
           }
  
           case 16:
           {
              png_bytep bp = row;
              png_uint_32 i;
              png_uint_32 istop = channels * row_width;
  
              for (i = 0; i < istop; i++)
              {
                 value = (png_uint_16)((*bp << 8) + *(bp + 1));
                 value >>= shift[i%channels];
                 *bp++ = (png_byte)(value >> 8);
                 *bp++ = (png_byte)(value & 0xff);
              }
              break;
           }
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_16_TO_8_SUPPORTED
  /* Chop rows of bit depth 16 down to 8 */
  void /* PRIVATE */
  png_do_chop(png_row_infop row_info, png_bytep row)
  {
     png_debug(1, "in png_do_chop");
  
     if (row_info->bit_depth == 16)
     {
        png_bytep sp = row;
        png_bytep dp = row;
        png_uint_32 i;
        png_uint_32 istop = row_info->width * row_info->channels;
  
        for (i = 0; i<istop; i++, sp += 2, dp++)
        {
  #ifdef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
        /* This does a more accurate scaling of the 16-bit color
         * value, rather than a simple low-byte truncation.
         *
         * What the ideal calculation should be:
         *   *dp = (((((png_uint_32)(*sp) << 8) |
         *          (png_uint_32)(*(sp + 1))) * 255 + 127)
         *          / (png_uint_32)65535L;
         *
         * GRR: no, I think this is what it really should be:
         *   *dp = (((((png_uint_32)(*sp) << 8) |
         *           (png_uint_32)(*(sp + 1))) + 128L)
         *           / (png_uint_32)257L;
         *
         * GRR: here's the exact calculation with shifts:
         *   temp = (((png_uint_32)(*sp) << 8) |
         *           (png_uint_32)(*(sp + 1))) + 128L;
         *   *dp = (temp - (temp >> 8)) >> 8;
         *
         * Approximate calculation with shift/add instead of multiply/divide:
         *   *dp = ((((png_uint_32)(*sp) << 8) |
         *          (png_uint_32)((int)(*(sp + 1)) - *sp)) + 128) >> 8;
         *
         * What we actually do to avoid extra shifting and conversion:
         */
  
           *dp = *sp + ((((int)(*(sp + 1)) - *sp) > 128) ? 1 : 0);
  #else
         /* Simply discard the low order byte */
           *dp = *sp;
  #endif
        }
        row_info->bit_depth = 8;
        row_info->pixel_depth = (png_byte)(8 * row_info->channels);
        row_info->rowbytes = row_info->width * row_info->channels;
     }
  }
  #endif
  
  #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
  void /* PRIVATE */
  png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
  {
     png_debug(1, "in png_do_read_swap_alpha");
  
     {
        png_uint_32 row_width = row_info->width;
        if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
        {
           /* This converts from RGBA to ARGB */
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_byte save;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 save = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = save;
              }
           }
           /* This converts from RRGGBBAA to AARRGGBB */
           else
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_byte save[2];
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 save[0] = *(--sp);
                 save[1] = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = save[0];
                 *(--dp) = save[1];
              }
           }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        {
           /* This converts from GA to AG */
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_byte save;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 save = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = save;
              }
           }
           /* This converts from GGAA to AAGG */
           else
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_byte save[2];
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 save[0] = *(--sp);
                 save[1] = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = save[0];
                 *(--dp) = save[1];
              }
           }
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
  void /* PRIVATE */
  png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
  {
     png_debug(1, "in png_do_read_invert_alpha");
  
     {
        png_uint_32 row_width = row_info->width;
        if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
        {
           /* This inverts the alpha channel in RGBA */
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = (png_byte)(255 - *(--sp));
  
  /*             This does nothing:
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 We can replace it with:
  */
                 sp-=3;
                 dp=sp;
              }
           }
           /* This inverts the alpha channel in RRGGBBAA */
           else
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = (png_byte)(255 - *(--sp));
                 *(--dp) = (png_byte)(255 - *(--sp));
  
  /*             This does nothing:
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 We can replace it with:
  */
                 sp-=6;
                 dp=sp;
              }
           }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        {
           /* This inverts the alpha channel in GA */
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = (png_byte)(255 - *(--sp));
                 *(--dp) = *(--sp);
              }
           }
           /* This inverts the alpha channel in GGAA */
           else
           {
              png_bytep sp  = row + row_info->rowbytes;
              png_bytep dp = sp;
              png_uint_32 i;
  
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = (png_byte)(255 - *(--sp));
                 *(--dp) = (png_byte)(255 - *(--sp));
  /*
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
  */
                 sp-=2;
                 dp=sp;
              }
           }
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_FILLER_SUPPORTED
  /* Add filler channel if we have RGB color */
  void /* PRIVATE */
  png_do_read_filler(png_row_infop row_info, png_bytep row,
     png_uint_32 filler, png_uint_32 flags)
  {
     png_uint_32 i;
     png_uint_32 row_width = row_info->width;
  
     png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
     png_byte lo_filler = (png_byte)(filler & 0xff);
  
     png_debug(1, "in png_do_read_filler");
  
     if (
         row_info->color_type == PNG_COLOR_TYPE_GRAY)
     {
        if (row_info->bit_depth == 8)
        {
           /* This changes the data from G to GX */
           if (flags & PNG_FLAG_FILLER_AFTER)
           {
              png_bytep sp = row + (png_size_t)row_width;
              png_bytep dp =  sp + (png_size_t)row_width;
              for (i = 1; i < row_width; i++)
              {
                 *(--dp) = lo_filler;
                 *(--dp) = *(--sp);
              }
              *(--dp) = lo_filler;
              row_info->channels = 2;
              row_info->pixel_depth = 16;
              row_info->rowbytes = row_width * 2;
           }
        /* This changes the data from G to XG */
           else
           {
              png_bytep sp = row + (png_size_t)row_width;
              png_bytep dp = sp  + (png_size_t)row_width;
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = *(--sp);
                 *(--dp) = lo_filler;
              }
              row_info->channels = 2;
              row_info->pixel_depth = 16;
              row_info->rowbytes = row_width * 2;
           }
        }
        else if (row_info->bit_depth == 16)
        {
           /* This changes the data from GG to GGXX */
           if (flags & PNG_FLAG_FILLER_AFTER)
           {
              png_bytep sp = row + (png_size_t)row_width * 2;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 1; i < row_width; i++)
              {
                 *(--dp) = hi_filler;
                 *(--dp) = lo_filler;
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
              }
              *(--dp) = hi_filler;
              *(--dp) = lo_filler;
              row_info->channels = 2;
              row_info->pixel_depth = 32;
              row_info->rowbytes = row_width * 4;
           }
           /* This changes the data from GG to XXGG */
           else
           {
              png_bytep sp = row + (png_size_t)row_width * 2;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = hi_filler;
                 *(--dp) = lo_filler;
              }
              row_info->channels = 2;
              row_info->pixel_depth = 32;
              row_info->rowbytes = row_width * 4;
           }
        }
     } /* COLOR_TYPE == GRAY */
     else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
     {
        if (row_info->bit_depth == 8)
        {
           /* This changes the data from RGB to RGBX */
           if (flags & PNG_FLAG_FILLER_AFTER)
           {
              png_bytep sp = row + (png_size_t)row_width * 3;
              png_bytep dp = sp  + (png_size_t)row_width;
              for (i = 1; i < row_width; i++)
              {
                 *(--dp) = lo_filler;
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
              }
              *(--dp) = lo_filler;
              row_info->channels = 4;
              row_info->pixel_depth = 32;
              row_info->rowbytes = row_width * 4;
           }
        /* This changes the data from RGB to XRGB */
           else
           {
              png_bytep sp = row + (png_size_t)row_width * 3;
              png_bytep dp = sp + (png_size_t)row_width;
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = lo_filler;
              }
              row_info->channels = 4;
              row_info->pixel_depth = 32;
              row_info->rowbytes = row_width * 4;
           }
        }
        else if (row_info->bit_depth == 16)
        {
           /* This changes the data from RRGGBB to RRGGBBXX */
           if (flags & PNG_FLAG_FILLER_AFTER)
           {
              png_bytep sp = row + (png_size_t)row_width * 6;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 1; i < row_width; i++)
              {
                 *(--dp) = hi_filler;
                 *(--dp) = lo_filler;
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
              }
              *(--dp) = hi_filler;
              *(--dp) = lo_filler;
              row_info->channels = 4;
              row_info->pixel_depth = 64;
              row_info->rowbytes = row_width * 8;
           }
           /* This changes the data from RRGGBB to XXRRGGBB */
           else
           {
              png_bytep sp = row + (png_size_t)row_width * 6;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 0; i < row_width; i++)
              {
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = *(--sp);
                 *(--dp) = hi_filler;
                 *(--dp) = lo_filler;
              }
              row_info->channels = 4;
              row_info->pixel_depth = 64;
              row_info->rowbytes = row_width * 8;
           }
        }
     } /* COLOR_TYPE == RGB */
  }
  #endif
  
  #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
  /* Expand grayscale files to RGB, with or without alpha */
  void /* PRIVATE */
  png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
  {
     png_uint_32 i;
     png_uint_32 row_width = row_info->width;
  
     png_debug(1, "in png_do_gray_to_rgb");
  
     if (row_info->bit_depth >= 8 &&
        !(row_info->color_type & PNG_COLOR_MASK_COLOR))
     {
        if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
        {
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + (png_size_t)row_width - 1;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 0; i < row_width; i++)
              {
                 *(dp--) = *sp;
                 *(dp--) = *sp;
                 *(dp--) = *(sp--);
              }
           }
           else
           {
              png_bytep sp = row + (png_size_t)row_width * 2 - 1;
              png_bytep dp = sp  + (png_size_t)row_width * 4;
              for (i = 0; i < row_width; i++)
              {
                 *(dp--) = *sp;
                 *(dp--) = *(sp - 1);
                 *(dp--) = *sp;
                 *(dp--) = *(sp - 1);
                 *(dp--) = *(sp--);
                 *(dp--) = *(sp--);
              }
           }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        {
           if (row_info->bit_depth == 8)
           {
              png_bytep sp = row + (png_size_t)row_width * 2 - 1;
              png_bytep dp = sp  + (png_size_t)row_width * 2;
              for (i = 0; i < row_width; i++)
              {
                 *(dp--) = *(sp--);
                 *(dp--) = *sp;
                 *(dp--) = *sp;
                 *(dp--) = *(sp--);
              }
           }
           else
           {
              png_bytep sp = row + (png_size_t)row_width * 4 - 1;
              png_bytep dp = sp  + (png_size_t)row_width * 4;
              for (i = 0; i < row_width; i++)
              {
                 *(dp--) = *(sp--);
                 *(dp--) = *(sp--);
                 *(dp--) = *sp;
                 *(dp--) = *(sp - 1);
                 *(dp--) = *sp;
                 *(dp--) = *(sp - 1);
                 *(dp--) = *(sp--);
                 *(dp--) = *(sp--);
              }
           }
        }
        row_info->channels += (png_byte)2;
        row_info->color_type |= PNG_COLOR_MASK_COLOR;
        row_info->pixel_depth = (png_byte)(row_info->channels *
           row_info->bit_depth);
        row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
     }
  }
  #endif
  
  #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
  /* Reduce RGB files to grayscale, with or without alpha
   * using the equation given in Poynton's ColorFAQ at
   * <http://www.inforamp.net/~poynton/>  (THIS LINK IS DEAD June 2008)
   * New link:
   * <http://www.poynton.com/notes/colour_and_gamma/>
   * Charles Poynton poynton at poynton.com
   *
   *     Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
   *
   *  We approximate this with
   *
   *     Y = 0.21268 * R    + 0.7151 * G    + 0.07217 * B
   *
   *  which can be expressed with integers as
   *
   *     Y = (6969 * R + 23434 * G + 2365 * B)/32768
   *
   *  The calculation is to be done in a linear colorspace.
   *
   *  Other integer coefficents can be used via png_set_rgb_to_gray().
   */
  int /* PRIVATE */
  png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
  
  {
     png_uint_32 i;
  
     png_uint_32 row_width = row_info->width;
     int rgb_error = 0;
  
     png_debug(1, "in png_do_rgb_to_gray");
  
     if (
        (row_info->color_type & PNG_COLOR_MASK_COLOR))
     {
        png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
        png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
        png_uint_32 bc = png_ptr->rgb_to_gray_blue_coeff;
  
        if (row_info->color_type == PNG_COLOR_TYPE_RGB)
        {
           if (row_info->bit_depth == 8)
           {
  #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
              if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
  
                 for (i = 0; i < row_width; i++)
                 {
                    png_byte red   = png_ptr->gamma_to_1[*(sp++)];
                    png_byte green = png_ptr->gamma_to_1[*(sp++)];
                    png_byte blue  = png_ptr->gamma_to_1[*(sp++)];
                    if (red != green || red != blue)
                    {
                       rgb_error |= 1;
                       *(dp++) = png_ptr->gamma_from_1[
                         (rc*red + gc*green + bc*blue)>>15];
                    }
                    else
                       *(dp++) = *(sp - 1);
                 }
              }
              else
  #endif
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_byte red   = *(sp++);
                    png_byte green = *(sp++);
                    png_byte blue  = *(sp++);
                    if (red != green || red != blue)
                    {
                       rgb_error |= 1;
                       *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
                    }
                    else
                       *(dp++) = *(sp - 1);
                 }
              }
           }
  
           else /* RGB bit_depth == 16 */
           {
  #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
              if (png_ptr->gamma_16_to_1 != NULL &&
                  png_ptr->gamma_16_from_1 != NULL)
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 red, green, blue, w;
  
                    red   = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    green = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    blue  = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
  
                    if (red == green && red == blue)
                       w = red;
                    else
                    {
                       png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red&0xff) >>
                                    png_ptr->gamma_shift][red>>8];
                       png_uint_16 green_1 =
                           png_ptr->gamma_16_to_1[(green&0xff) >>
                                    png_ptr->gamma_shift][green>>8];
                       png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue&0xff) >>
                                    png_ptr->gamma_shift][blue>>8];
                       png_uint_16 gray16  = (png_uint_16)((rc*red_1 + gc*green_1
                                    + bc*blue_1)>>15);
                       w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
                           png_ptr->gamma_shift][gray16 >> 8];
                       rgb_error |= 1;
                    }
  
                    *(dp++) = (png_byte)((w>>8) & 0xff);
                    *(dp++) = (png_byte)(w & 0xff);
                 }
              }
              else
  #endif
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 red, green, blue, gray16;
  
                    red   = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    green = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    blue  = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
  
                    if (red != green || red != blue)
                       rgb_error |= 1;
                    gray16  = (png_uint_16)((rc*red + gc*green + bc*blue)>>15);
                    *(dp++) = (png_byte)((gray16>>8) & 0xff);
                    *(dp++) = (png_byte)(gray16 & 0xff);
                 }
              }
           }
        }
        if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
        {
           if (row_info->bit_depth == 8)
           {
  #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
              if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_byte red   = png_ptr->gamma_to_1[*(sp++)];
                    png_byte green = png_ptr->gamma_to_1[*(sp++)];
                    png_byte blue  = png_ptr->gamma_to_1[*(sp++)];
                    if (red != green || red != blue)
                       rgb_error |= 1;
                    *(dp++) =  png_ptr->gamma_from_1
                               [(rc*red + gc*green + bc*blue)>>15];
                    *(dp++) = *(sp++);  /* alpha */
                 }
              }
              else
  #endif
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_byte red   = *(sp++);
                    png_byte green = *(sp++);
                    png_byte blue  = *(sp++);
                    if (red != green || red != blue)
                       rgb_error |= 1;
                    *(dp++) =  (png_byte)((rc*red + gc*green + bc*blue)>>15);
                    *(dp++) = *(sp++);  /* alpha */
                 }
              }
           }
           else /* RGBA bit_depth == 16 */
           {
  #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
              if (png_ptr->gamma_16_to_1 != NULL &&
                  png_ptr->gamma_16_from_1 != NULL)
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 red, green, blue, w;
  
                    red   = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    green = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
                    blue  = (png_uint_16)(((*(sp))<<8) | *(sp+1)); sp+=2;
  
                    if (red == green && red == blue)
                       w = red;
                    else
                    {
                       png_uint_16 red_1   = png_ptr->gamma_16_to_1[(red&0xff) >>
                           png_ptr->gamma_shift][red>>8];
                       png_uint_16 green_1 =
                           png_ptr->gamma_16_to_1[(green&0xff) >>
                           png_ptr->gamma_shift][green>>8];
                       png_uint_16 blue_1  = png_ptr->gamma_16_to_1[(blue&0xff) >>
                           png_ptr->gamma_shift][blue>>8];
                       png_uint_16 gray16  = (png_uint_16)((rc * red_1
                           + gc * green_1 + bc * blue_1)>>15);
                       w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
                           png_ptr->gamma_shift][gray16 >> 8];
                       rgb_error |= 1;
                    }
  
                    *(dp++) = (png_byte)((w>>8) & 0xff);
                    *(dp++) = (png_byte)(w & 0xff);
                    *(dp++) = *(sp++);  /* alpha */
                    *(dp++) = *(sp++);
                 }
              }
              else
  #endif
              {
                 png_bytep sp = row;
                 png_bytep dp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 red, green, blue, gray16;
                    red   = (png_uint_16)((*(sp)<<8) | *(sp+1)); sp+=2;
                    green = (png_uint_16)((*(sp)<<8) | *(sp+1)); sp+=2;
                    blue  = (png_uint_16)((*(sp)<<8) | *(sp+1)); sp+=2;
                    if (red != green || red != blue)
                       rgb_error |= 1;
                    gray16  = (png_uint_16)((rc*red + gc*green + bc*blue)>>15);
                    *(dp++) = (png_byte)((gray16>>8) & 0xff);
                    *(dp++) = (png_byte)(gray16 & 0xff);
                    *(dp++) = *(sp++);  /* alpha */
                    *(dp++) = *(sp++);
                 }
              }
           }
        }
     row_info->channels -= (png_byte)2;
        row_info->color_type &= ~PNG_COLOR_MASK_COLOR;
        row_info->pixel_depth = (png_byte)(row_info->channels *
           row_info->bit_depth);
        row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
     }
     return rgb_error;
  }
  #endif
  
  /* Build a grayscale palette.  Palette is assumed to be 1 << bit_depth
   * large of png_color.  This lets grayscale images be treated as
   * paletted.  Most useful for gamma correction and simplification
   * of code.
   */
  void PNGAPI
  png_build_grayscale_palette(int bit_depth, png_colorp palette)
  {
     int num_palette;
     int color_inc;
     int i;
     int v;
  
     png_debug(1, "in png_do_build_grayscale_palette");
  
     if (palette == NULL)
        return;
  
     switch (bit_depth)
     {
        case 1:
           num_palette = 2;
           color_inc = 0xff;
           break;
  
        case 2:
           num_palette = 4;
           color_inc = 0x55;
           break;
  
        case 4:
           num_palette = 16;
           color_inc = 0x11;
           break;
  
        case 8:
           num_palette = 256;
           color_inc = 1;
           break;
  
        default:
           num_palette = 0;
           color_inc = 0;
           break;
     }
  
     for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
     {
        palette[i].red = (png_byte)v;
        palette[i].green = (png_byte)v;
        palette[i].blue = (png_byte)v;
     }
  }
  
  
  #ifdef PNG_READ_BACKGROUND_SUPPORTED
  /* Replace any alpha or transparency with the supplied background color.
   * "background" is already in the screen gamma, while "background_1" is
   * at a gamma of 1.0.  Paletted files have already been taken care of.
   */
  void /* PRIVATE */
  png_do_background(png_row_infop row_info, png_bytep row,
     png_color_16p trans_color, png_color_16p background
  #ifdef PNG_READ_GAMMA_SUPPORTED
     , png_color_16p background_1,
     png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
     png_uint_16pp gamma_16, png_uint_16pp gamma_16_from_1,
     png_uint_16pp gamma_16_to_1, int gamma_shift
  #endif
     )
  {
     png_bytep sp, dp;
     png_uint_32 i;
     png_uint_32 row_width=row_info->width;
     int shift;
  
     png_debug(1, "in png_do_background");
  
     if (background != NULL &&
        (!(row_info->color_type & PNG_COLOR_MASK_ALPHA) ||
        (row_info->color_type != PNG_COLOR_TYPE_PALETTE && trans_color)))
     {
        switch (row_info->color_type)
        {
           case PNG_COLOR_TYPE_GRAY:
           {
              switch (row_info->bit_depth)
              {
                 case 1:
                 {
                    sp = row;
                    shift = 7;
                    for (i = 0; i < row_width; i++)
                    {
                       if ((png_uint_16)((*sp >> shift) & 0x01)
                          == trans_color->gray)
                       {
                          *sp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
                          *sp |= (png_byte)(background->gray << shift);
                       }
                       if (!shift)
                       {
                          shift = 7;
                          sp++;
                       }
                       else
                          shift--;
                    }
                    break;
                 }
  
                 case 2:
                 {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                    if (gamma_table != NULL)
                    {
                       sp = row;
                       shift = 6;
                       for (i = 0; i < row_width; i++)
                       {
                          if ((png_uint_16)((*sp >> shift) & 0x03)
                              == trans_color->gray)
                          {
                             *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
                             *sp |= (png_byte)(background->gray << shift);
                          }
                          else
                          {
                             png_byte p = (png_byte)((*sp >> shift) & 0x03);
                             png_byte g = (png_byte)((gamma_table [p | (p << 2) |
                                 (p << 4) | (p << 6)] >> 6) & 0x03);
                             *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
                             *sp |= (png_byte)(g << shift);
                          }
                          if (!shift)
                          {
                             shift = 6;
                             sp++;
                          }
                          else
                             shift -= 2;
                       }
                    }
                    else
  #endif
                    {
                       sp = row;
                       shift = 6;
                       for (i = 0; i < row_width; i++)
                       {
                          if ((png_uint_16)((*sp >> shift) & 0x03)
                              == trans_color->gray)
                          {
                             *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
                             *sp |= (png_byte)(background->gray << shift);
                          }
                          if (!shift)
                          {
                             shift = 6;
                             sp++;
                          }
                          else
                             shift -= 2;
                       }
                    }
                    break;
                 }
  
                 case 4:
                 {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                    if (gamma_table != NULL)
                    {
                       sp = row;
                       shift = 4;
                       for (i = 0; i < row_width; i++)
                       {
                          if ((png_uint_16)((*sp >> shift) & 0x0f)
                              == trans_color->gray)
                          {
                             *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
                             *sp |= (png_byte)(background->gray << shift);
                          }
                          else
                          {
                             png_byte p = (png_byte)((*sp >> shift) & 0x0f);
                             png_byte g = (png_byte)((gamma_table[p |
                               (p << 4)] >> 4) & 0x0f);
                             *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
                             *sp |= (png_byte)(g << shift);
                          }
                          if (!shift)
                          {
                             shift = 4;
                             sp++;
                          }
                          else
                             shift -= 4;
                       }
                    }
                    else
  #endif
                    {
                       sp = row;
                       shift = 4;
                       for (i = 0; i < row_width; i++)
                       {
                          if ((png_uint_16)((*sp >> shift) & 0x0f)
                              == trans_color->gray)
                          {
                             *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
                             *sp |= (png_byte)(background->gray << shift);
                          }
                          if (!shift)
                          {
                             shift = 4;
                             sp++;
                          }
                          else
                             shift -= 4;
                       }
                    }
                    break;
                 }
  
                 case 8:
                 {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                    if (gamma_table != NULL)
                    {
                       sp = row;
                       for (i = 0; i < row_width; i++, sp++)
                       {
                          if (*sp == trans_color->gray)
                          {
                             *sp = (png_byte)background->gray;
                          }
                          else
                          {
                             *sp = gamma_table[*sp];
                          }
                       }
                    }
                    else
  #endif
                    {
                       sp = row;
                       for (i = 0; i < row_width; i++, sp++)
                       {
                          if (*sp == trans_color->gray)
                          {
                             *sp = (png_byte)background->gray;
                          }
                       }
                    }
                    break;
                 }
  
                 case 16:
                 {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                    if (gamma_16 != NULL)
                    {
                       sp = row;
                       for (i = 0; i < row_width; i++, sp += 2)
                       {
                          png_uint_16 v;
  
                          v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
                          if (v == trans_color->gray)
                          {
                             /* Background is already in screen gamma */
                             *sp = (png_byte)((background->gray >> 8) & 0xff);
                             *(sp + 1) = (png_byte)(background->gray & 0xff);
                          }
                          else
                          {
                             v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
                             *sp = (png_byte)((v >> 8) & 0xff);
                             *(sp + 1) = (png_byte)(v & 0xff);
                          }
                       }
                    }
                    else
  #endif
                    {
                       sp = row;
                       for (i = 0; i < row_width; i++, sp += 2)
                       {
                          png_uint_16 v;
  
                          v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
                          if (v == trans_color->gray)
                          {
                             *sp = (png_byte)((background->gray >> 8) & 0xff);
                             *(sp + 1) = (png_byte)(background->gray & 0xff);
                          }
                       }
                    }
                    break;
                 }
  
                 default:
                    break;
              }
              break;
           }
  
           case PNG_COLOR_TYPE_RGB:
           {
              if (row_info->bit_depth == 8)
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_table != NULL)
                 {
                    sp = row;
                    for (i = 0; i < row_width; i++, sp += 3)
                    {
                       if (*sp == trans_color->red &&
                          *(sp + 1) == trans_color->green &&
                          *(sp + 2) == trans_color->blue)
                       {
                          *sp = (png_byte)background->red;
                          *(sp + 1) = (png_byte)background->green;
                          *(sp + 2) = (png_byte)background->blue;
                       }
                       else
                       {
                          *sp = gamma_table[*sp];
                          *(sp + 1) = gamma_table[*(sp + 1)];
                          *(sp + 2) = gamma_table[*(sp + 2)];
                       }
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    for (i = 0; i < row_width; i++, sp += 3)
                    {
                       if (*sp == trans_color->red &&
                          *(sp + 1) == trans_color->green &&
                          *(sp + 2) == trans_color->blue)
                       {
                          *sp = (png_byte)background->red;
                          *(sp + 1) = (png_byte)background->green;
                          *(sp + 2) = (png_byte)background->blue;
                       }
                    }
                 }
              }
              else /* if (row_info->bit_depth == 16) */
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_16 != NULL)
                 {
                    sp = row;
                    for (i = 0; i < row_width; i++, sp += 6)
                    {
                       png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
                       png_uint_16 g = (png_uint_16)(((*(sp+2)) << 8) + *(sp+3));
                       png_uint_16 b = (png_uint_16)(((*(sp+4)) << 8) + *(sp+5));
                       if (r == trans_color->red && g == trans_color->green &&
                          b == trans_color->blue)
                       {
                          /* Background is already in screen gamma */
                          *sp = (png_byte)((background->red >> 8) & 0xff);
                          *(sp + 1) = (png_byte)(background->red & 0xff);
                          *(sp + 2) = (png_byte)((background->green >> 8) & 0xff);
                          *(sp + 3) = (png_byte)(background->green & 0xff);
                          *(sp + 4) = (png_byte)((background->blue >> 8) & 0xff);
                          *(sp + 5) = (png_byte)(background->blue & 0xff);
                       }
                       else
                       {
                          png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
                          *sp = (png_byte)((v >> 8) & 0xff);
                          *(sp + 1) = (png_byte)(v & 0xff);
                          v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
                          *(sp + 2) = (png_byte)((v >> 8) & 0xff);
                          *(sp + 3) = (png_byte)(v & 0xff);
                          v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
                          *(sp + 4) = (png_byte)((v >> 8) & 0xff);
                          *(sp + 5) = (png_byte)(v & 0xff);
                       }
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    for (i = 0; i < row_width; i++, sp += 6)
                    {
                       png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp+1));
                       png_uint_16 g = (png_uint_16)(((*(sp+2)) << 8) + *(sp+3));
                       png_uint_16 b = (png_uint_16)(((*(sp+4)) << 8) + *(sp+5));
  
                       if (r == trans_color->red && g == trans_color->green &&
                          b == trans_color->blue)
                       {
                          *sp = (png_byte)((background->red >> 8) & 0xff);
                          *(sp + 1) = (png_byte)(background->red & 0xff);
                          *(sp + 2) = (png_byte)((background->green >> 8) & 0xff);
                          *(sp + 3) = (png_byte)(background->green & 0xff);
                          *(sp + 4) = (png_byte)((background->blue >> 8) & 0xff);
                          *(sp + 5) = (png_byte)(background->blue & 0xff);
                       }
                    }
                 }
              }
              break;
           }
  
           case PNG_COLOR_TYPE_GRAY_ALPHA:
           {
              if (row_info->bit_depth == 8)
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
                     gamma_table != NULL)
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 2, dp++)
                    {
                       png_uint_16 a = *(sp + 1);
  
                       if (a == 0xff)
                       {
                          *dp = gamma_table[*sp];
                       }
                       else if (a == 0)
                       {
                          /* Background is already in screen gamma */
                          *dp = (png_byte)background->gray;
                       }
                       else
                       {
                          png_byte v, w;
  
                          v = gamma_to_1[*sp];
                          png_composite(w, v, a, background_1->gray);
                          *dp = gamma_from_1[w];
                       }
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 2, dp++)
                    {
                       png_byte a = *(sp + 1);
  
                       if (a == 0xff)
                       {
                          *dp = *sp;
                       }
  #ifdef PNG_READ_GAMMA_SUPPORTED
                       else if (a == 0)
                       {
                          *dp = (png_byte)background->gray;
                       }
                       else
                       {
                          png_composite(*dp, *sp, a, background_1->gray);
                       }
  #else
                       *dp = (png_byte)background->gray;
  #endif
                    }
                 }
              }
              else /* if (png_ptr->bit_depth == 16) */
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
                     gamma_16_to_1 != NULL)
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 4, dp += 2)
                    {
                       png_uint_16 a = (png_uint_16)(((*(sp+2)) << 8) + *(sp+3));
  
                       if (a == (png_uint_16)0xffff)
                       {
                          png_uint_16 v;
  
                          v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
                          *dp = (png_byte)((v >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(v & 0xff);
                       }
  #ifdef PNG_READ_GAMMA_SUPPORTED
                       else if (a == 0)
  #else
                       else
  #endif
                       {
                          /* Background is already in screen gamma */
                          *dp = (png_byte)((background->gray >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(background->gray & 0xff);
                       }
  #ifdef PNG_READ_GAMMA_SUPPORTED
                       else
                       {
                          png_uint_16 g, v, w;
  
                          g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
                          png_composite_16(v, g, a, background_1->gray);
                          w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
                          *dp = (png_byte)((w >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(w & 0xff);
                       }
  #endif
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 4, dp += 2)
                    {
                       png_uint_16 a = (png_uint_16)(((*(sp+2)) << 8) + *(sp+3));
                       if (a == (png_uint_16)0xffff)
                       {
                          png_memcpy(dp, sp, 2);
                       }
  #ifdef PNG_READ_GAMMA_SUPPORTED
                       else if (a == 0)
  #else
                       else
  #endif
                       {
                          *dp = (png_byte)((background->gray >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(background->gray & 0xff);
                       }
  #ifdef PNG_READ_GAMMA_SUPPORTED
                       else
                       {
                          png_uint_16 g, v;
  
                          g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
                          png_composite_16(v, g, a, background_1->gray);
                          *dp = (png_byte)((v >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(v & 0xff);
                       }
  #endif
                    }
                 }
              }
              break;
           }
  
           case PNG_COLOR_TYPE_RGB_ALPHA:
           {
              if (row_info->bit_depth == 8)
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
                     gamma_table != NULL)
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 4, dp += 3)
                    {
                       png_byte a = *(sp + 3);
  
                       if (a == 0xff)
                       {
                          *dp = gamma_table[*sp];
                          *(dp + 1) = gamma_table[*(sp + 1)];
                          *(dp + 2) = gamma_table[*(sp + 2)];
                       }
                       else if (a == 0)
                       {
                          /* Background is already in screen gamma */
                          *dp = (png_byte)background->red;
                          *(dp + 1) = (png_byte)background->green;
                          *(dp + 2) = (png_byte)background->blue;
                       }
                       else
                       {
                          png_byte v, w;
  
                          v = gamma_to_1[*sp];
                          png_composite(w, v, a, background_1->red);
                          *dp = gamma_from_1[w];
                          v = gamma_to_1[*(sp + 1)];
                          png_composite(w, v, a, background_1->green);
                          *(dp + 1) = gamma_from_1[w];
                          v = gamma_to_1[*(sp + 2)];
                          png_composite(w, v, a, background_1->blue);
                          *(dp + 2) = gamma_from_1[w];
                       }
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 4, dp += 3)
                    {
                       png_byte a = *(sp + 3);
  
                       if (a == 0xff)
                       {
                          *dp = *sp;
                          *(dp + 1) = *(sp + 1);
                          *(dp + 2) = *(sp + 2);
                       }
                       else if (a == 0)
                       {
                          *dp = (png_byte)background->red;
                          *(dp + 1) = (png_byte)background->green;
                          *(dp + 2) = (png_byte)background->blue;
                       }
                       else
                       {
                          png_composite(*dp, *sp, a, background->red);
                          png_composite(*(dp + 1), *(sp + 1), a,
                             background->green);
                          png_composite(*(dp + 2), *(sp + 2), a,
                             background->blue);
                       }
                    }
                 }
              }
              else /* if (row_info->bit_depth == 16) */
              {
  #ifdef PNG_READ_GAMMA_SUPPORTED
                 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
                     gamma_16_to_1 != NULL)
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 8, dp += 6)
                    {
                       png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
                           << 8) + (png_uint_16)(*(sp + 7)));
                       if (a == (png_uint_16)0xffff)
                       {
                          png_uint_16 v;
  
                          v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
                          *dp = (png_byte)((v >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(v & 0xff);
                          v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
                          *(dp + 2) = (png_byte)((v >> 8) & 0xff);
                          *(dp + 3) = (png_byte)(v & 0xff);
                          v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
                          *(dp + 4) = (png_byte)((v >> 8) & 0xff);
                          *(dp + 5) = (png_byte)(v & 0xff);
                       }
                       else if (a == 0)
                       {
                          /* Background is already in screen gamma */
                          *dp = (png_byte)((background->red >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(background->red & 0xff);
                          *(dp + 2) = (png_byte)((background->green >> 8) & 0xff);
                          *(dp + 3) = (png_byte)(background->green & 0xff);
                          *(dp + 4) = (png_byte)((background->blue >> 8) & 0xff);
                          *(dp + 5) = (png_byte)(background->blue & 0xff);
                       }
                       else
                       {
                          png_uint_16 v, w, x;
  
                          v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
                          png_composite_16(w, v, a, background_1->red);
                          x = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
                          *dp = (png_byte)((x >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(x & 0xff);
                          v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
                          png_composite_16(w, v, a, background_1->green);
                          x = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
                          *(dp + 2) = (png_byte)((x >> 8) & 0xff);
                          *(dp + 3) = (png_byte)(x & 0xff);
                          v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
                          png_composite_16(w, v, a, background_1->blue);
                          x = gamma_16_from_1[(w & 0xff) >> gamma_shift][w >> 8];
                          *(dp + 4) = (png_byte)((x >> 8) & 0xff);
                          *(dp + 5) = (png_byte)(x & 0xff);
                       }
                    }
                 }
                 else
  #endif
                 {
                    sp = row;
                    dp = row;
                    for (i = 0; i < row_width; i++, sp += 8, dp += 6)
                    {
                       png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
                          << 8) + (png_uint_16)(*(sp + 7)));
                       if (a == (png_uint_16)0xffff)
                       {
                          png_memcpy(dp, sp, 6);
                       }
                       else if (a == 0)
                       {
                          *dp = (png_byte)((background->red >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(background->red & 0xff);
                          *(dp + 2) = (png_byte)((background->green >> 8) & 0xff);
                          *(dp + 3) = (png_byte)(background->green & 0xff);
                          *(dp + 4) = (png_byte)((background->blue >> 8) & 0xff);
                          *(dp + 5) = (png_byte)(background->blue & 0xff);
                       }
                       else
                       {
                          png_uint_16 v;
  
                          png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
                          png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
                              + *(sp + 3));
                          png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
                              + *(sp + 5));
  
                          png_composite_16(v, r, a, background->red);
                          *dp = (png_byte)((v >> 8) & 0xff);
                          *(dp + 1) = (png_byte)(v & 0xff);
                          png_composite_16(v, g, a, background->green);
                          *(dp + 2) = (png_byte)((v >> 8) & 0xff);
                          *(dp + 3) = (png_byte)(v & 0xff);
                          png_composite_16(v, b, a, background->blue);
                          *(dp + 4) = (png_byte)((v >> 8) & 0xff);
                          *(dp + 5) = (png_byte)(v & 0xff);
                       }
                    }
                 }
              }
              break;
           }
  
           default:
              break;
        }
  
        if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
        {
           row_info->color_type &= ~PNG_COLOR_MASK_ALPHA;
           row_info->channels--;
           row_info->pixel_depth = (png_byte)(row_info->channels *
              row_info->bit_depth);
           row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_GAMMA_SUPPORTED
  /* Gamma correct the image, avoiding the alpha channel.  Make sure
   * you do this after you deal with the transparency issue on grayscale
   * or RGB images. If your bit depth is 8, use gamma_table, if it
   * is 16, use gamma_16_table and gamma_shift.  Build these with
   * build_gamma_table().
   */
  void /* PRIVATE */
  png_do_gamma(png_row_infop row_info, png_bytep row,
     png_bytep gamma_table, png_uint_16pp gamma_16_table,
     int gamma_shift)
  {
     png_bytep sp;
     png_uint_32 i;
     png_uint_32 row_width=row_info->width;
  
     png_debug(1, "in png_do_gamma");
  
     if (
         ((row_info->bit_depth <= 8 && gamma_table != NULL) ||
          (row_info->bit_depth == 16 && gamma_16_table != NULL)))
     {
        switch (row_info->color_type)
        {
           case PNG_COLOR_TYPE_RGB:
           {
              if (row_info->bit_depth == 8)
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    *sp = gamma_table[*sp];
                    sp++;
                    *sp = gamma_table[*sp];
                    sp++;
                    *sp = gamma_table[*sp];
                    sp++;
                 }
              }
              else /* if (row_info->bit_depth == 16) */
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 v;
  
                    v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                    v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                    v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                 }
              }
              break;
           }
  
           case PNG_COLOR_TYPE_RGB_ALPHA:
           {
              if (row_info->bit_depth == 8)
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    *sp = gamma_table[*sp];
                    sp++;
                    *sp = gamma_table[*sp];
                    sp++;
                    *sp = gamma_table[*sp];
                    sp++;
                    sp++;
                 }
              }
              else /* if (row_info->bit_depth == 16) */
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                    v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                    v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 4;
                 }
              }
              break;
           }
  
           case PNG_COLOR_TYPE_GRAY_ALPHA:
           {
              if (row_info->bit_depth == 8)
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    *sp = gamma_table[*sp];
                    sp += 2;
                 }
              }
              else /* if (row_info->bit_depth == 16) */
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 4;
                 }
              }
              break;
           }
  
           case PNG_COLOR_TYPE_GRAY:
           {
              if (row_info->bit_depth == 2)
              {
                 sp = row;
                 for (i = 0; i < row_width; i += 4)
                 {
                    int a = *sp & 0xc0;
                    int b = *sp & 0x30;
                    int c = *sp & 0x0c;
                    int d = *sp & 0x03;
  
                    *sp = (png_byte)(
                        ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)])   ) & 0xc0)|
                        ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
                        ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
                        ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
                    sp++;
                 }
              }
  
              if (row_info->bit_depth == 4)
              {
                 sp = row;
                 for (i = 0; i < row_width; i += 2)
                 {
                    int msb = *sp & 0xf0;
                    int lsb = *sp & 0x0f;
  
                    *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
                        | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
                    sp++;
                 }
              }
  
              else if (row_info->bit_depth == 8)
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    *sp = gamma_table[*sp];
                    sp++;
                 }
              }
  
              else if (row_info->bit_depth == 16)
              {
                 sp = row;
                 for (i = 0; i < row_width; i++)
                 {
                    png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
                    *sp = (png_byte)((v >> 8) & 0xff);
                    *(sp + 1) = (png_byte)(v & 0xff);
                    sp += 2;
                 }
              }
              break;
           }
  
           default:
              break;
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_EXPAND_SUPPORTED
  /* Expands a palette row to an RGB or RGBA row depending
   * upon whether you supply trans and num_trans.
   */
  void /* PRIVATE */
  png_do_expand_palette(png_row_infop row_info, png_bytep row,
     png_colorp palette, png_bytep trans_alpha, int num_trans)
  {
     int shift, value;
     png_bytep sp, dp;
     png_uint_32 i;
     png_uint_32 row_width=row_info->width;
  
     png_debug(1, "in png_do_expand_palette");
  
     if (
         row_info->color_type == PNG_COLOR_TYPE_PALETTE)
     {
        if (row_info->bit_depth < 8)
        {
           switch (row_info->bit_depth)
           {
              case 1:
              {
                 sp = row + (png_size_t)((row_width - 1) >> 3);
                 dp = row + (png_size_t)row_width - 1;
                 shift = 7 - (int)((row_width + 7) & 0x07);
                 for (i = 0; i < row_width; i++)
                 {
                    if ((*sp >> shift) & 0x01)
                       *dp = 1;
                    else
                       *dp = 0;
                    if (shift == 7)
                    {
                       shift = 0;
                       sp--;
                    }
                    else
                       shift++;
  
                    dp--;
                 }
                 break;
              }
  
              case 2:
              {
                 sp = row + (png_size_t)((row_width - 1) >> 2);
                 dp = row + (png_size_t)row_width - 1;
                 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
                 for (i = 0; i < row_width; i++)
                 {
                    value = (*sp >> shift) & 0x03;
                    *dp = (png_byte)value;
                    if (shift == 6)
                    {
                       shift = 0;
                       sp--;
                    }
                    else
                       shift += 2;
  
                    dp--;
                 }
                 break;
              }
  
              case 4:
              {
                 sp = row + (png_size_t)((row_width - 1) >> 1);
                 dp = row + (png_size_t)row_width - 1;
                 shift = (int)((row_width & 0x01) << 2);
                 for (i = 0; i < row_width; i++)
                 {
                    value = (*sp >> shift) & 0x0f;
                    *dp = (png_byte)value;
                    if (shift == 4)
                    {
                       shift = 0;
                       sp--;
                    }
                    else
                       shift += 4;
  
                    dp--;
                 }
                 break;
              }
  
              default:
                 break;
           }
           row_info->bit_depth = 8;
           row_info->pixel_depth = 8;
           row_info->rowbytes = row_width;
        }
        switch (row_info->bit_depth)
        {
           case 8:
           {
              if (trans_alpha != NULL)
              {
                 sp = row + (png_size_t)row_width - 1;
                 dp = row + (png_size_t)(row_width << 2) - 1;
  
                 for (i = 0; i < row_width; i++)
                 {
                    if ((int)(*sp) >= num_trans)
                       *dp-- = 0xff;
                    else
                       *dp-- = trans_alpha[*sp];
                    *dp-- = palette[*sp].blue;
                    *dp-- = palette[*sp].green;
                    *dp-- = palette[*sp].red;
                    sp--;
                 }
                 row_info->bit_depth = 8;
                 row_info->pixel_depth = 32;
                 row_info->rowbytes = row_width * 4;
                 row_info->color_type = 6;
                 row_info->channels = 4;
              }
              else
              {
                 sp = row + (png_size_t)row_width - 1;
                 dp = row + (png_size_t)(row_width * 3) - 1;
  
                 for (i = 0; i < row_width; i++)
                 {
                    *dp-- = palette[*sp].blue;
                    *dp-- = palette[*sp].green;
                    *dp-- = palette[*sp].red;
                    sp--;
                 }
  
                 row_info->bit_depth = 8;
                 row_info->pixel_depth = 24;
                 row_info->rowbytes = row_width * 3;
                 row_info->color_type = 2;
                 row_info->channels = 3;
              }
              break;
           }
        }
     }
  }
  
  /* If the bit depth < 8, it is expanded to 8.  Also, if the already
   * expanded transparency value is supplied, an alpha channel is built.
   */
  void /* PRIVATE */
  png_do_expand(png_row_infop row_info, png_bytep row,
     png_color_16p trans_value)
  {
     int shift, value;
     png_bytep sp, dp;
     png_uint_32 i;
     png_uint_32 row_width=row_info->width;
  
     png_debug(1, "in png_do_expand");
  
     {
        if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
        {
           png_uint_16 gray = (png_uint_16)(trans_value ? trans_value->gray : 0);
  
           if (row_info->bit_depth < 8)
           {
              switch (row_info->bit_depth)
              {
                 case 1:
                 {
                    gray = (png_uint_16)((gray&0x01)*0xff);
                    sp = row + (png_size_t)((row_width - 1) >> 3);
                    dp = row + (png_size_t)row_width - 1;
                    shift = 7 - (int)((row_width + 7) & 0x07);
                    for (i = 0; i < row_width; i++)
                    {
                       if ((*sp >> shift) & 0x01)
                          *dp = 0xff;
                       else
                          *dp = 0;
                       if (shift == 7)
                       {
                          shift = 0;
                          sp--;
                       }
                       else
                          shift++;
  
                       dp--;
                    }
                    break;
                 }
  
                 case 2:
                 {
                    gray = (png_uint_16)((gray&0x03)*0x55);
                    sp = row + (png_size_t)((row_width - 1) >> 2);
                    dp = row + (png_size_t)row_width - 1;
                    shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
                    for (i = 0; i < row_width; i++)
                    {
                       value = (*sp >> shift) & 0x03;
                       *dp = (png_byte)(value | (value << 2) | (value << 4) |
                          (value << 6));
                       if (shift == 6)
                       {
                          shift = 0;
                          sp--;
                       }
                       else
                          shift += 2;
  
                       dp--;
                    }
                    break;
                 }
  
                 case 4:
                 {
                    gray = (png_uint_16)((gray&0x0f)*0x11);
                    sp = row + (png_size_t)((row_width - 1) >> 1);
                    dp = row + (png_size_t)row_width - 1;
                    shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
                    for (i = 0; i < row_width; i++)
                    {
                       value = (*sp >> shift) & 0x0f;
                       *dp = (png_byte)(value | (value << 4));
                       if (shift == 4)
                       {
                          shift = 0;
                          sp--;
                       }
                       else
                          shift = 4;
  
                       dp--;
                    }
                    break;
                 }
  
                 default:
                    break;
              }
  
              row_info->bit_depth = 8;
              row_info->pixel_depth = 8;
              row_info->rowbytes = row_width;
           }
  
           if (trans_value != NULL)
           {
              if (row_info->bit_depth == 8)
              {
                 gray = gray & 0xff;
                 sp = row + (png_size_t)row_width - 1;
                 dp = row + (png_size_t)(row_width << 1) - 1;
                 for (i = 0; i < row_width; i++)
                 {
                    if (*sp == gray)
                       *dp-- = 0;
                    else
                       *dp-- = 0xff;
                    *dp-- = *sp--;
                 }
              }
  
              else if (row_info->bit_depth == 16)
              {
                 png_byte gray_high = (gray >> 8) & 0xff;
                 png_byte gray_low = gray & 0xff;
                 sp = row + row_info->rowbytes - 1;
                 dp = row + (row_info->rowbytes << 1) - 1;
                 for (i = 0; i < row_width; i++)
                 {
                    if (*(sp - 1) == gray_high && *(sp) == gray_low)
                    {
                       *dp-- = 0;
                       *dp-- = 0;
                    }
                    else
                    {
                       *dp-- = 0xff;
                       *dp-- = 0xff;
                    }
                    *dp-- = *sp--;
                    *dp-- = *sp--;
                 }
              }
  
              row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
              row_info->channels = 2;
              row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
              row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
                 row_width);
           }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_value)
        {
           if (row_info->bit_depth == 8)
           {
              png_byte red = trans_value->red & 0xff;
              png_byte green = trans_value->green & 0xff;
              png_byte blue = trans_value->blue & 0xff;
              sp = row + (png_size_t)row_info->rowbytes - 1;
              dp = row + (png_size_t)(row_width << 2) - 1;
              for (i = 0; i < row_width; i++)
              {
                 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
                    *dp-- = 0;
                 else
                    *dp-- = 0xff;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
              }
           }
           else if (row_info->bit_depth == 16)
           {
              png_byte red_high = (trans_value->red >> 8) & 0xff;
              png_byte green_high = (trans_value->green >> 8) & 0xff;
              png_byte blue_high = (trans_value->blue >> 8) & 0xff;
              png_byte red_low = trans_value->red & 0xff;
              png_byte green_low = trans_value->green & 0xff;
              png_byte blue_low = trans_value->blue & 0xff;
              sp = row + row_info->rowbytes - 1;
              dp = row + (png_size_t)(row_width << 3) - 1;
              for (i = 0; i < row_width; i++)
              {
                 if (*(sp - 5) == red_high &&
                    *(sp - 4) == red_low &&
                    *(sp - 3) == green_high &&
                    *(sp - 2) == green_low &&
                    *(sp - 1) == blue_high &&
                    *(sp    ) == blue_low)
                 {
                    *dp-- = 0;
                    *dp-- = 0;
                 }
                 else
                 {
                    *dp-- = 0xff;
                    *dp-- = 0xff;
                 }
                 *dp-- = *sp--;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
                 *dp-- = *sp--;
              }
           }
           row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
           row_info->channels = 4;
           row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
           row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
        }
     }
  }
  #endif
  
  #ifdef PNG_READ_QUANTIZE_SUPPORTED
  void /* PRIVATE */
  png_do_quantize(png_row_infop row_info, png_bytep row,
      png_bytep palette_lookup, png_bytep quantize_lookup)
  {
     png_bytep sp, dp;
     png_uint_32 i;
     png_uint_32 row_width=row_info->width;
  
     png_debug(1, "in png_do_quantize");
  
     {
        if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
           palette_lookup && row_info->bit_depth == 8)
        {
           int r, g, b, p;
           sp = row;
           dp = row;
           for (i = 0; i < row_width; i++)
           {
              r = *sp++;
              g = *sp++;
              b = *sp++;
  
              /* This looks real messy, but the compiler will reduce
               * it down to a reasonable formula.  For example, with
               * 5 bits per color, we get:
               * p = (((r >> 3) & 0x1f) << 10) |
               *    (((g >> 3) & 0x1f) << 5) |
               *    ((b >> 3) & 0x1f);
               */
              p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
                 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
                 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
                 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
                 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
                 (PNG_QUANTIZE_BLUE_BITS)) |
                 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
                 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
  
              *dp++ = palette_lookup[p];
           }
           row_info->color_type = PNG_COLOR_TYPE_PALETTE;
           row_info->channels = 1;
           row_info->pixel_depth = row_info->bit_depth;
           row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
           palette_lookup != NULL && row_info->bit_depth == 8)
        {
           int r, g, b, p;
           sp = row;
           dp = row;
           for (i = 0; i < row_width; i++)
           {
              r = *sp++;
              g = *sp++;
              b = *sp++;
              sp++;
  
              p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
                 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
                 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
                 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
                 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
                 (PNG_QUANTIZE_BLUE_BITS)) |
                 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
                 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
  
              *dp++ = palette_lookup[p];
           }
           row_info->color_type = PNG_COLOR_TYPE_PALETTE;
           row_info->channels = 1;
           row_info->pixel_depth = row_info->bit_depth;
           row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
           quantize_lookup && row_info->bit_depth == 8)
        {
           sp = row;
           for (i = 0; i < row_width; i++, sp++)
           {
              *sp = quantize_lookup[*sp];
           }
        }
     }
  }
  #endif
  
  #ifdef PNG_FLOATING_POINT_SUPPORTED
  #ifdef PNG_READ_GAMMA_SUPPORTED
  static PNG_CONST int png_gamma_shift[] =
     {0x10, 0x21, 0x42, 0x84, 0x110, 0x248, 0x550, 0xff0, 0x00};
  
  /* We build the 8- or 16-bit gamma tables here.  Note that for 16-bit
   * tables, we don't make a full table if we are reducing to 8-bit in
   * the future.  Note also how the gamma_16 tables are segmented so that
   * we don't need to allocate > 64K chunks for a full 16-bit table.
   *
   * See the PNG extensions document for an integer algorithm for creating
   * the gamma tables.  Maybe we will implement that here someday.
   *
   * We should only reach this point if
   *
   *      the file_gamma is known (i.e., the gAMA or sRGB chunk is present,
   *      or the application has provided a file_gamma)
   *
   *   AND
   *      {
   *         the screen_gamma is known
   *
   *      OR
   *
   *         RGB_to_gray transformation is being performed
   *      }
   *
   *   AND
   *      {
   *         the screen_gamma is different from the reciprocal of the
   *         file_gamma by more than the specified threshold
   *
   *      OR
   *
   *         a background color has been specified and the file_gamma
   *         and screen_gamma are not 1.0, within the specified threshold.
   *      }
   */
  
  void /* PRIVATE */
  png_build_gamma_table(png_structp png_ptr, png_byte bit_depth)
  {
    png_debug(1, "in png_build_gamma_table");
  
    if (bit_depth <= 8)
    {
       int i;
       double g;
  
       if (png_ptr->screen_gamma > .000001)
          g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
  
       else
          g = 1.0;
  
       png_ptr->gamma_table = (png_bytep)png_malloc(png_ptr,
          (png_uint_32)256);
  
       for (i = 0; i < 256; i++)
       {
          png_ptr->gamma_table[i] = (png_byte)(pow((double)i / 255.0,
             g) * 255.0 + .5);
       }
  
  #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
     defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
       if (png_ptr->transformations & ((PNG_BACKGROUND) | PNG_RGB_TO_GRAY))
       {
  
          g = 1.0 / (png_ptr->gamma);
  
          png_ptr->gamma_to_1 = (png_bytep)png_malloc(png_ptr,
             (png_uint_32)256);
  
          for (i = 0; i < 256; i++)
          {
             png_ptr->gamma_to_1[i] = (png_byte)(pow((double)i / 255.0,
                g) * 255.0 + .5);
          }
  
  
          png_ptr->gamma_from_1 = (png_bytep)png_malloc(png_ptr,
             (png_uint_32)256);
  
          if (png_ptr->screen_gamma > 0.000001)
             g = 1.0 / png_ptr->screen_gamma;
  
          else
             g = png_ptr->gamma;   /* Probably doing rgb_to_gray */
  
          for (i = 0; i < 256; i++)
          {
             png_ptr->gamma_from_1[i] = (png_byte)(pow((double)i / 255.0,
                g) * 255.0 + .5);
  
          }
       }
  #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
    }
    else
    {
       double g;
       int i, j, shift, num;
       int sig_bit;
       png_uint_32 ig;
  
       if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
       {
          sig_bit = (int)png_ptr->sig_bit.red;
  
          if ((int)png_ptr->sig_bit.green > sig_bit)
             sig_bit = png_ptr->sig_bit.green;
  
          if ((int)png_ptr->sig_bit.blue > sig_bit)
             sig_bit = png_ptr->sig_bit.blue;
       }
       else
       {
          sig_bit = (int)png_ptr->sig_bit.gray;
       }
  
       if (sig_bit > 0)
          shift = 16 - sig_bit;
  
       else
          shift = 0;
  
       if (png_ptr->transformations & PNG_16_TO_8)
       {
          if (shift < (16 - PNG_MAX_GAMMA_8))
             shift = (16 - PNG_MAX_GAMMA_8);
       }
  
       if (shift > 8)
          shift = 8;
  
       if (shift < 0)
          shift = 0;
  
       png_ptr->gamma_shift = (png_byte)shift;
  
       num = (1 << (8 - shift));
  
       if (png_ptr->screen_gamma > .000001)
          g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
       else
          g = 1.0;
  
       png_ptr->gamma_16_table = (png_uint_16pp)png_calloc(png_ptr,
          (png_uint_32)(num * png_sizeof(png_uint_16p)));
  
       if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND))
       {
          double fin, fout;
          png_uint_32 last, max;
  
          for (i = 0; i < num; i++)
          {
             png_ptr->gamma_16_table[i] = (png_uint_16p)png_malloc(png_ptr,
                (png_uint_32)(256 * png_sizeof(png_uint_16)));
          }
  
          g = 1.0 / g;
          last = 0;
          for (i = 0; i < 256; i++)
          {
             fout = ((double)i + 0.5) / 256.0;
             fin = pow(fout, g);
             max = (png_uint_32)(fin * (double)((png_uint_32)num << 8));
             while (last <= max)
             {
                png_ptr->gamma_16_table[(int)(last & (0xff >> shift))]
                   [(int)(last >> (8 - shift))] = (png_uint_16)(
                   (png_uint_16)i | ((png_uint_16)i << 8));
                last++;
             }
          }
          while (last < ((png_uint_32)num << 8))
          {
             png_ptr->gamma_16_table[(int)(last & (0xff >> shift))]
                [(int)(last >> (8 - shift))] = (png_uint_16)65535L;
             last++;
          }
       }
       else
       {
          for (i = 0; i < num; i++)
          {
             png_ptr->gamma_16_table[i] = (png_uint_16p)png_malloc(png_ptr,
                (png_uint_32)(256 * png_sizeof(png_uint_16)));
  
             ig = (((png_uint_32)i * (png_uint_32)png_gamma_shift[shift]) >> 4);
  
             for (j = 0; j < 256; j++)
             {
                png_ptr->gamma_16_table[i][j] =
                   (png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
                      65535.0, g) * 65535.0 + .5);
             }
          }
       }
  
  #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
     defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
       if (png_ptr->transformations & (PNG_BACKGROUND | PNG_RGB_TO_GRAY))
       {
  
          g = 1.0 / (png_ptr->gamma);
  
          png_ptr->gamma_16_to_1 = (png_uint_16pp)png_calloc(png_ptr,
             (png_uint_32)(num * png_sizeof(png_uint_16p )));
  
          for (i = 0; i < num; i++)
          {
             png_ptr->gamma_16_to_1[i] = (png_uint_16p)png_malloc(png_ptr,
                (png_uint_32)(256 * png_sizeof(png_uint_16)));
  
             ig = (((png_uint_32)i *
                (png_uint_32)png_gamma_shift[shift]) >> 4);
             for (j = 0; j < 256; j++)
             {
                png_ptr->gamma_16_to_1[i][j] =
                   (png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
                      65535.0, g) * 65535.0 + .5);
             }
          }
  
          if (png_ptr->screen_gamma > 0.000001)
             g = 1.0 / png_ptr->screen_gamma;
  
          else
             g = png_ptr->gamma;   /* Probably doing rgb_to_gray */
  
          png_ptr->gamma_16_from_1 = (png_uint_16pp)png_calloc(png_ptr,
             (png_uint_32)(num * png_sizeof(png_uint_16p)));
  
          for (i = 0; i < num; i++)
          {
             png_ptr->gamma_16_from_1[i] = (png_uint_16p)png_malloc(png_ptr,
                (png_uint_32)(256 * png_sizeof(png_uint_16)));
  
             ig = (((png_uint_32)i *
                (png_uint_32)png_gamma_shift[shift]) >> 4);
  
             for (j = 0; j < 256; j++)
             {
                png_ptr->gamma_16_from_1[i][j] =
                   (png_uint_16)(pow((double)(ig + ((png_uint_32)j << 8)) /
                      65535.0, g) * 65535.0 + .5);
             }
          }
       }
  #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */
    }
  }
  #endif
  /* To do: install integer version of png_build_gamma_table here */
  #endif
  
  #ifdef PNG_MNG_FEATURES_SUPPORTED
  /* Undoes intrapixel differencing  */
  void /* PRIVATE */
  png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
  {
     png_debug(1, "in png_do_read_intrapixel");
  
     if (
         (row_info->color_type & PNG_COLOR_MASK_COLOR))
     {
        int bytes_per_pixel;
        png_uint_32 row_width = row_info->width;
        if (row_info->bit_depth == 8)
        {
           png_bytep rp;
           png_uint_32 i;
  
           if (row_info->color_type == PNG_COLOR_TYPE_RGB)
              bytes_per_pixel = 3;
  
           else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
              bytes_per_pixel = 4;
  
           else
              return;
  
           for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
           {
              *(rp) = (png_byte)((256 + *rp + *(rp+1))&0xff);
              *(rp+2) = (png_byte)((256 + *(rp+2) + *(rp+1))&0xff);
           }
        }
        else if (row_info->bit_depth == 16)
        {
           png_bytep rp;
           png_uint_32 i;
  
           if (row_info->color_type == PNG_COLOR_TYPE_RGB)
              bytes_per_pixel = 6;
  
           else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
              bytes_per_pixel = 8;
  
           else
              return;
  
           for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
           {
              png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
              png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
              png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
              png_uint_32 red  = (png_uint_32)((s0 + s1 + 65536L) & 0xffffL);
              png_uint_32 blue = (png_uint_32)((s2 + s1 + 65536L) & 0xffffL);
              *(rp  ) = (png_byte)((red >> 8) & 0xff);
              *(rp+1) = (png_byte)(red & 0xff);
              *(rp+4) = (png_byte)((blue >> 8) & 0xff);
              *(rp+5) = (png_byte)(blue & 0xff);
           }
        }
     }
  }
  #endif /* PNG_MNG_FEATURES_SUPPORTED */
  #endif /* PNG_READ_SUPPORTED */
  