text: /* stb_image_write - v1.11 - public domain - http://nothings.org/stb/stb_image_write.h
     writes out PNG/BMP/TGA/JPEG/HDR images to C stdio - Sean Barrett 2010-2015
                                       no warranty implied; use at your own risk
  
     Before #including,
  
         #define STB_IMAGE_WRITE_IMPLEMENTATION
  
     in the file that you want to have the implementation.
  
     Will probably not work correctly with strict-aliasing optimizations.
  
     If using a modern Microsoft Compiler, non-safe versions of CRT calls may cause 
     compilation warnings or even errors. To avoid this, also before #including,
  
         #define STBI_MSC_SECURE_CRT
  
  ABOUT:
  
     This header file is a library for writing images to C stdio or a callback.
  
     The PNG output is not optimal; it is 20-50% larger than the file
     written by a decent optimizing implementation; though providing a custom
     zlib compress function (see STBIW_ZLIB_COMPRESS) can mitigate that.
     This library is designed for source code compactness and simplicity,
     not optimal image file size or run-time performance.
  
  BUILDING:
  
     You can #define STBIW_ASSERT(x) before the #include to avoid using assert.h.
     You can #define STBIW_MALLOC(), STBIW_REALLOC(), and STBIW_FREE() to replace
     malloc,realloc,free.
     You can #define STBIW_MEMMOVE() to replace memmove()
     You can #define STBIW_ZLIB_COMPRESS to use a custom zlib-style compress function
     for PNG compression (instead of the builtin one), it must have the following signature:
     unsigned char * my_compress(unsigned char *data, int data_len, int *out_len, int quality);
     The returned data will be freed with STBIW_FREE() (free() by default),
     so it must be heap allocated with STBIW_MALLOC() (malloc() by default),
  
  UNICODE:
  
     If compiling for Windows and you wish to use Unicode filenames, compile
     with
         #define STBIW_WINDOWS_UTF8
     and pass utf8-encoded filenames. Call stbiw_convert_wchar_to_utf8 to convert
     Windows wchar_t filenames to utf8.
  
  USAGE:
  
     There are five functions, one for each image file format:
  
       int stbi_write_png(char const *filename, int w, int h, int comp, const void *data, int stride_in_bytes);
       int stbi_write_bmp(char const *filename, int w, int h, int comp, const void *data);
       int stbi_write_tga(char const *filename, int w, int h, int comp, const void *data);
       int stbi_write_jpg(char const *filename, int w, int h, int comp, const void *data, int quality);
       int stbi_write_hdr(char const *filename, int w, int h, int comp, const float *data);
  
       void stbi_flip_vertically_on_write(int flag); // flag is non-zero to flip data vertically
  
     There are also five equivalent functions that use an arbitrary write function. You are
     expected to open/close your file-equivalent before and after calling these:
  
       int stbi_write_png_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data, int stride_in_bytes);
       int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);
       int stbi_write_tga_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);
       int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const float *data);
       int stbi_write_jpg_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data, int quality);
  
     where the callback is:
        void stbi_write_func(void *context, void *data, int size);
  
     You can configure it with these global variables:
        int stbi_write_tga_with_rle;             // defaults to true; set to 0 to disable RLE
        int stbi_write_png_compression_level;    // defaults to 8; set to higher for more compression
        int stbi_write_force_png_filter;         // defaults to -1; set to 0..5 to force a filter mode
  
  
     You can define STBI_WRITE_NO_STDIO to disable the file variant of these
     functions, so the library will not use stdio.h at all. However, this will
     also disable HDR writing, because it requires stdio for formatted output.
  
     Each function returns 0 on failure and non-0 on success.
  
     The functions create an image file defined by the parameters. The image
     is a rectangle of pixels stored from left-to-right, top-to-bottom.
     Each pixel contains 'comp' channels of data stored interleaved with 8-bits
     per channel, in the following order: 1=Y, 2=YA, 3=RGB, 4=RGBA. (Y is
     monochrome color.) The rectangle is 'w' pixels wide and 'h' pixels tall.
     The *data pointer points to the first byte of the top-left-most pixel.
     For PNG, "stride_in_bytes" is the distance in bytes from the first byte of
     a row of pixels to the first byte of the next row of pixels.
  
     PNG creates output files with the same number of components as the input.
     The BMP format expands Y to RGB in the file format and does not
     output alpha.
  
     PNG supports writing rectangles of data even when the bytes storing rows of
     data are not consecutive in memory (e.g. sub-rectangles of a larger image),
     by supplying the stride between the beginning of adjacent rows. The other
     formats do not. (Thus you cannot write a native-format BMP through the BMP
     writer, both because it is in BGR order and because it may have padding
     at the end of the line.)
  
     PNG allows you to set the deflate compression level by setting the global
     variable 'stbi_write_png_compression_level' (it defaults to 8).
  
     HDR expects linear float data. Since the format is always 32-bit rgb(e)
     data, alpha (if provided) is discarded, and for monochrome data it is
     replicated across all three channels.
  
     TGA supports RLE or non-RLE compressed data. To use non-RLE-compressed
     data, set the global variable 'stbi_write_tga_with_rle' to 0.
     
     JPEG does ignore alpha channels in input data; quality is between 1 and 100.
     Higher quality looks better but results in a bigger image.
     JPEG baseline (no JPEG progressive).
  
  CREDITS:
  
  
     Sean Barrett           -    PNG/BMP/TGA 
     Baldur Karlsson        -    HDR
     Jean-Sebastien Guay    -    TGA monochrome
     Tim Kelsey             -    misc enhancements
     Alan Hickman           -    TGA RLE
     Emmanuel Julien        -    initial file IO callback implementation
     Jon Olick              -    original jo_jpeg.cpp code
     Daniel Gibson          -    integrate JPEG, allow external zlib
     Aarni Koskela          -    allow choosing PNG filter
  
     bugfixes:
        github:Chribba
        Guillaume Chereau
        github:jry2
        github:romigrou
        Sergio Gonzalez
        Jonas Karlsson
        Filip Wasil
        Thatcher Ulrich
        github:poppolopoppo
        Patrick Boettcher
        github:xeekworx
        Cap Petschulat
        Simon Rodriguez
        Ivan Tikhonov
        github:ignotion
        Adam Schackart
  
  LICENSE
  
    See end of file for license information.
  
  */
  
  #ifndef INCLUDE_STB_IMAGE_WRITE_H
  #define INCLUDE_STB_IMAGE_WRITE_H
  
  #include <stdlib.h>
  
  #pragma warning(push)
  #pragma warning(disable : 4996)
  
  // if STB_IMAGE_WRITE_STATIC causes problems, try defining STBIWDEF to 'inline' or 'static inline'
  #ifndef STBIWDEF
  #ifdef STB_IMAGE_WRITE_STATIC
  #define STBIWDEF  static
  #else
  #ifdef __cplusplus
  #define STBIWDEF  extern "C"
  #else
  #define STBIWDEF  extern
  #endif
  #endif
  #endif
  
  #ifndef STB_IMAGE_WRITE_STATIC  // C++ forbids static forward declarations
  extern int stbi_write_tga_with_rle;
  extern int stbi_write_png_compression_level;
  extern int stbi_write_force_png_filter;
  #endif
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_png(char const *filename, int w, int h, int comp, const void  *data, int stride_in_bytes);
  STBIWDEF int stbi_write_bmp(char const *filename, int w, int h, int comp, const void  *data);
  STBIWDEF int stbi_write_tga(char const *filename, int w, int h, int comp, const void  *data);
  STBIWDEF int stbi_write_hdr(char const *filename, int w, int h, int comp, const float *data);
  STBIWDEF int stbi_write_jpg(char const *filename, int x, int y, int comp, const void  *data, int quality);
  
  #ifdef STBI_WINDOWS_UTF8
  STBIWDEF int stbiw_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input);
  #endif
  #endif
  
  typedef void stbi_write_func(void *context, void *data, int size);
  
  STBIWDEF int stbi_write_png_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data, int stride_in_bytes);
  STBIWDEF int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);
  STBIWDEF int stbi_write_tga_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);
  STBIWDEF int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const float *data);
  STBIWDEF int stbi_write_jpg_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void  *data, int quality);
  
  STBIWDEF void stbi_flip_vertically_on_write(int flip_boolean);
  
  #endif//INCLUDE_STB_IMAGE_WRITE_H
  
  #ifdef STB_IMAGE_WRITE_IMPLEMENTATION
  
  #ifdef _WIN32
     #ifndef _CRT_SECURE_NO_WARNINGS
     #define _CRT_SECURE_NO_WARNINGS
     #endif
     #ifndef _CRT_NONSTDC_NO_DEPRECATE
     #define _CRT_NONSTDC_NO_DEPRECATE
     #endif
  #endif
  
  #ifndef STBI_WRITE_NO_STDIO
  #include <stdio.h>
  #endif // STBI_WRITE_NO_STDIO
  
  #include <stdarg.h>
  #include <stdlib.h>
  #include <string.h>
  #include <math.h>
  
  #if defined(STBIW_MALLOC) && defined(STBIW_FREE) && (defined(STBIW_REALLOC) || defined(STBIW_REALLOC_SIZED))
  // ok
  #elif !defined(STBIW_MALLOC) && !defined(STBIW_FREE) && !defined(STBIW_REALLOC) && !defined(STBIW_REALLOC_SIZED)
  // ok
  #else
  #error "Must define all or none of STBIW_MALLOC, STBIW_FREE, and STBIW_REALLOC (or STBIW_REALLOC_SIZED)."
  #endif
  
  #ifndef STBIW_MALLOC
  #define STBIW_MALLOC(sz)        malloc(sz)
  #define STBIW_REALLOC(p,newsz)  realloc(p,newsz)
  #define STBIW_FREE(p)           free(p)
  #endif
  
  #ifndef STBIW_REALLOC_SIZED
  #define STBIW_REALLOC_SIZED(p,oldsz,newsz) STBIW_REALLOC(p,newsz)
  #endif
  
  
  #ifndef STBIW_MEMMOVE
  #define STBIW_MEMMOVE(a,b,sz) memmove(a,b,sz)
  #endif
  
  
  #ifndef STBIW_ASSERT
  #include <assert.h>
  #define STBIW_ASSERT(x) assert(x)
  #endif
  
  #define STBIW_UCHAR(x) (unsigned char) ((x) & 0xff)
  
  #ifdef STB_IMAGE_WRITE_STATIC
  static int stbi__flip_vertically_on_write=0;
  static int stbi_write_png_compression_level = 8;
  static int stbi_write_tga_with_rle = 1;
  static int stbi_write_force_png_filter = -1;
  #else
  int stbi_write_png_compression_level = 8;
  int stbi__flip_vertically_on_write=0;
  int stbi_write_tga_with_rle = 1;
  int stbi_write_force_png_filter = -1;
  #endif
  
  STBIWDEF void stbi_flip_vertically_on_write(int flag)
  {
     stbi__flip_vertically_on_write = flag;
  }
  
  typedef struct
  {
     stbi_write_func *func;
     void *context;
  } stbi__write_context;
  
  // initialize a callback-based context
  static void stbi__start_write_callbacks(stbi__write_context *s, stbi_write_func *c, void *context)
  {
     s->func    = c;
     s->context = context;
  }
  
  #ifndef STBI_WRITE_NO_STDIO
  
  static void stbi__stdio_write(void *context, void *data, int size)
  {
     fwrite(data,1,size,(FILE*) context);
  }
  
  #if defined(_MSC_VER) && defined(STBI_WINDOWS_UTF8)
  #ifdef __cplusplus
  #define STBIW_EXTERN extern "C"
  #else
  #define STBIW_EXTERN extern
  #endif
  STBIW_EXTERN __declspec(dllimport) int __stdcall MultiByteToWideChar(unsigned int cp, unsigned long flags, const char *str, int cbmb, wchar_t *widestr, int cchwide);
  STBIW_EXTERN __declspec(dllimport) int __stdcall WideCharToMultiByte(unsigned int cp, unsigned long flags, const wchar_t *widestr, int cchwide, char *str, int cbmb, const char *defchar, int *used_default);
  
  STBIWDEF int stbiw_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input)
  {
  	return WideCharToMultiByte(65001 /* UTF8 */, 0, input, -1, buffer, bufferlen, NULL, NULL);
  }
  #endif
  
  static FILE *stbiw__fopen(char const *filename, char const *mode)
  {
     FILE *f;
  #if defined(_MSC_VER) && defined(STBI_WINDOWS_UTF8)
     wchar_t wMode[64];
     wchar_t wFilename[1024];
  	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, filename, -1, wFilename, sizeof(wFilename)))
        return 0;
  	
  	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, mode, -1, wMode, sizeof(wMode)))
        return 0;
  
  #if _MSC_VER >= 1400
  	if (0 != _wfopen_s(&f, wFilename, wMode))
  		f = 0;
  #else
     f = _wfopen(wFilename, wMode);
  #endif
  
  #elif defined(_MSC_VER) && _MSC_VER >= 1400
     if (0 != fopen_s(&f, filename, mode))
        f=0;
  #else
     f = fopen(filename, mode);
  #endif
     return f;
  }
  
  static int stbi__start_write_file(stbi__write_context *s, const char *filename)
  {
     FILE *f = stbiw__fopen(filename, "wb");
     stbi__start_write_callbacks(s, stbi__stdio_write, (void *) f);
     return f != NULL;
  }
  
  static void stbi__end_write_file(stbi__write_context *s)
  {
     fclose((FILE *)s->context);
  }
  
  #endif // !STBI_WRITE_NO_STDIO
  
  typedef unsigned int stbiw_uint32;
  typedef int stb_image_write_test[sizeof(stbiw_uint32)==4 ? 1 : -1];
  
  static void stbiw__writefv(stbi__write_context *s, const char *fmt, va_list v)
  {
     while (*fmt) {
        switch (*fmt++) {
           case ' ': break;
           case '1': { unsigned char x = STBIW_UCHAR(va_arg(v, int));
                       s->func(s->context,&x,1);
                       break; }
           case '2': { int x = va_arg(v,int);
                       unsigned char b[2];
                       b[0] = STBIW_UCHAR(x);
                       b[1] = STBIW_UCHAR(x>>8);
                       s->func(s->context,b,2);
                       break; }
           case '4': { stbiw_uint32 x = va_arg(v,int);
                       unsigned char b[4];
                       b[0]=STBIW_UCHAR(x);
                       b[1]=STBIW_UCHAR(x>>8);
                       b[2]=STBIW_UCHAR(x>>16);
                       b[3]=STBIW_UCHAR(x>>24);
                       s->func(s->context,b,4);
                       break; }
           default:
              STBIW_ASSERT(0);
              return;
        }
     }
  }
  
  static void stbiw__writef(stbi__write_context *s, const char *fmt, ...)
  {
     va_list v;
     va_start(v, fmt);
     stbiw__writefv(s, fmt, v);
     va_end(v);
  }
  
  static void stbiw__putc(stbi__write_context *s, unsigned char c)
  {
     s->func(s->context, &c, 1);
  }
  
  static void stbiw__write3(stbi__write_context *s, unsigned char a, unsigned char b, unsigned char c)
  {
     unsigned char arr[3];
     arr[0] = a, arr[1] = b, arr[2] = c;
     s->func(s->context, arr, 3);
  }
  
  static void stbiw__write_pixel(stbi__write_context *s, int rgb_dir, int comp, int write_alpha, int expand_mono, unsigned char *d)
  {
     unsigned char bg[3] = { 255, 0, 255}, px[3];
     int k;
  
     if (write_alpha < 0)
        s->func(s->context, &d[comp - 1], 1);
  
     switch (comp) {
        case 2: // 2 pixels = mono + alpha, alpha is written separately, so same as 1-channel case
        case 1:
           if (expand_mono)
              stbiw__write3(s, d[0], d[0], d[0]); // monochrome bmp
           else
              s->func(s->context, d, 1);  // monochrome TGA
           break;
        case 4:
           if (!write_alpha) {
              // composite against pink background
              for (k = 0; k < 3; ++k)
                 px[k] = bg[k] + ((d[k] - bg[k]) * d[3]) / 255;
              stbiw__write3(s, px[1 - rgb_dir], px[1], px[1 + rgb_dir]);
              break;
           }
           /* FALLTHROUGH */
        case 3:
           stbiw__write3(s, d[1 - rgb_dir], d[1], d[1 + rgb_dir]);
           break;
     }
     if (write_alpha > 0)
        s->func(s->context, &d[comp - 1], 1);
  }
  
  static void stbiw__write_pixels(stbi__write_context *s, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad, int expand_mono)
  {
     stbiw_uint32 zero = 0;
     int i,j, j_end;
  
     if (y <= 0)
        return;
  
     if (stbi__flip_vertically_on_write)
        vdir *= -1;
  
     if (vdir < 0)
        j_end = -1, j = y-1;
     else
        j_end =  y, j = 0;
  
     for (; j != j_end; j += vdir) {
        for (i=0; i < x; ++i) {
           unsigned char *d = (unsigned char *) data + (j*x+i)*comp;
           stbiw__write_pixel(s, rgb_dir, comp, write_alpha, expand_mono, d);
        }
        s->func(s->context, &zero, scanline_pad);
     }
  }
  
  static int stbiw__outfile(stbi__write_context *s, int rgb_dir, int vdir, int x, int y, int comp, int expand_mono, void *data, int alpha, int pad, const char *fmt, ...)
  {
     if (y < 0 || x < 0) {
        return 0;
     } else {
        va_list v;
        va_start(v, fmt);
        stbiw__writefv(s, fmt, v);
        va_end(v);
        stbiw__write_pixels(s,rgb_dir,vdir,x,y,comp,data,alpha,pad, expand_mono);
        return 1;
     }
  }
  
  static int stbi_write_bmp_core(stbi__write_context *s, int x, int y, int comp, const void *data)
  {
     int pad = (-x*3) & 3;
     return stbiw__outfile(s,-1,-1,x,y,comp,1,(void *) data,0,pad,
             "11 4 22 4" "4 44 22 444444",
             'B', 'M', 14+40+(x*3+pad)*y, 0,0, 14+40,  // file header
              40, x,y, 1,24, 0,0,0,0,0,0);             // bitmap header
  }
  
  STBIWDEF int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data)
  {
     stbi__write_context s;
     stbi__start_write_callbacks(&s, func, context);
     return stbi_write_bmp_core(&s, x, y, comp, data);
  }
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_bmp(char const *filename, int x, int y, int comp, const void *data)
  {
     stbi__write_context s;
     if (stbi__start_write_file(&s,filename)) {
        int r = stbi_write_bmp_core(&s, x, y, comp, data);
        stbi__end_write_file(&s);
        return r;
     } else
        return 0;
  }
  #endif //!STBI_WRITE_NO_STDIO
  
  static int stbi_write_tga_core(stbi__write_context *s, int x, int y, int comp, void *data)
  {
     int has_alpha = (comp == 2 || comp == 4);
     int colorbytes = has_alpha ? comp-1 : comp;
     int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 2, 1 color channel (Y/YA) = 3
  
     if (y < 0 || x < 0)
        return 0;
  
     if (!stbi_write_tga_with_rle) {
        return stbiw__outfile(s, -1, -1, x, y, comp, 0, (void *) data, has_alpha, 0,
           "111 221 2222 11", 0, 0, format, 0, 0, 0, 0, 0, x, y, (colorbytes + has_alpha) * 8, has_alpha * 8);
     } else {
        int i,j,k;
        int jend, jdir;
  
        stbiw__writef(s, "111 221 2222 11", 0,0,format+8, 0,0,0, 0,0,x,y, (colorbytes + has_alpha) * 8, has_alpha * 8);
  
        if (stbi__flip_vertically_on_write) {
           j = 0;
           jend = y;
           jdir = 1;
        } else {
           j = y-1;
           jend = -1;
           jdir = -1;
        }
        for (; j != jend; j += jdir) {
           unsigned char *row = (unsigned char *) data + j * x * comp;
           int len;
  
           for (i = 0; i < x; i += len) {
              unsigned char *begin = row + i * comp;
              int diff = 1;
              len = 1;
  
              if (i < x - 1) {
                 ++len;
                 diff = memcmp(begin, row + (i + 1) * comp, comp);
                 if (diff) {
                    const unsigned char *prev = begin;
                    for (k = i + 2; k < x && len < 128; ++k) {
                       if (memcmp(prev, row + k * comp, comp)) {
                          prev += comp;
                          ++len;
                       } else {
                          --len;
                          break;
                       }
                    }
                 } else {
                    for (k = i + 2; k < x && len < 128; ++k) {
                       if (!memcmp(begin, row + k * comp, comp)) {
                          ++len;
                       } else {
                          break;
                       }
                    }
                 }
              }
  
              if (diff) {
                 unsigned char header = STBIW_UCHAR(len - 1);
                 s->func(s->context, &header, 1);
                 for (k = 0; k < len; ++k) {
                    stbiw__write_pixel(s, -1, comp, has_alpha, 0, begin + k * comp);
                 }
              } else {
                 unsigned char header = STBIW_UCHAR(len - 129);
                 s->func(s->context, &header, 1);
                 stbiw__write_pixel(s, -1, comp, has_alpha, 0, begin);
              }
           }
        }
     }
     return 1;
  }
  
  STBIWDEF int stbi_write_tga_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data)
  {
     stbi__write_context s;
     stbi__start_write_callbacks(&s, func, context);
     return stbi_write_tga_core(&s, x, y, comp, (void *) data);
  }
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_tga(char const *filename, int x, int y, int comp, const void *data)
  {
     stbi__write_context s;
     if (stbi__start_write_file(&s,filename)) {
        int r = stbi_write_tga_core(&s, x, y, comp, (void *) data);
        stbi__end_write_file(&s);
        return r;
     } else
        return 0;
  }
  #endif
  
  // *************************************************************************************************
  // Radiance RGBE HDR writer
  // by Baldur Karlsson
  
  #define stbiw__max(a, b)  ((a) > (b) ? (a) : (b))
  
  static void stbiw__linear_to_rgbe(unsigned char *rgbe, float *linear)
  {
     int exponent;
     float maxcomp = stbiw__max(linear[0], stbiw__max(linear[1], linear[2]));
  
     if (maxcomp < 1e-32f) {
        rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;
     } else {
        float normalize = (float) frexp(maxcomp, &exponent) * 256.0f/maxcomp;
  
        rgbe[0] = (unsigned char)(linear[0] * normalize);
        rgbe[1] = (unsigned char)(linear[1] * normalize);
        rgbe[2] = (unsigned char)(linear[2] * normalize);
        rgbe[3] = (unsigned char)(exponent + 128);
     }
  }
  
  static void stbiw__write_run_data(stbi__write_context *s, int length, unsigned char databyte)
  {
     unsigned char lengthbyte = STBIW_UCHAR(length+128);
     STBIW_ASSERT(length+128 <= 255);
     s->func(s->context, &lengthbyte, 1);
     s->func(s->context, &databyte, 1);
  }
  
  static void stbiw__write_dump_data(stbi__write_context *s, int length, unsigned char *data)
  {
     unsigned char lengthbyte = STBIW_UCHAR(length);
     STBIW_ASSERT(length <= 128); // inconsistent with spec but consistent with official code
     s->func(s->context, &lengthbyte, 1);
     s->func(s->context, data, length);
  }
  
  static void stbiw__write_hdr_scanline(stbi__write_context *s, int width, int ncomp, unsigned char *scratch, float *scanline)
  {
     unsigned char scanlineheader[4] = { 2, 2, 0, 0 };
     unsigned char rgbe[4];
     float linear[3];
     int x;
  
     scanlineheader[2] = (width&0xff00)>>8;
     scanlineheader[3] = (width&0x00ff);
  
     /* skip RLE for images too small or large */
     if (width < 8 || width >= 32768) {
        for (x=0; x < width; x++) {
           switch (ncomp) {
              case 4: /* fallthrough */
              case 3: linear[2] = scanline[x*ncomp + 2];
                      linear[1] = scanline[x*ncomp + 1];
                      linear[0] = scanline[x*ncomp + 0];
                      break;
              default:
                      linear[0] = linear[1] = linear[2] = scanline[x*ncomp + 0];
                      break;
           }
           stbiw__linear_to_rgbe(rgbe, linear);
           s->func(s->context, rgbe, 4);
        }
     } else {
        int c,r;
        /* encode into scratch buffer */
        for (x=0; x < width; x++) {
           switch(ncomp) {
              case 4: /* fallthrough */
              case 3: linear[2] = scanline[x*ncomp + 2];
                      linear[1] = scanline[x*ncomp + 1];
                      linear[0] = scanline[x*ncomp + 0];
                      break;
              default:
                      linear[0] = linear[1] = linear[2] = scanline[x*ncomp + 0];
                      break;
           }
           stbiw__linear_to_rgbe(rgbe, linear);
           scratch[x + width*0] = rgbe[0];
           scratch[x + width*1] = rgbe[1];
           scratch[x + width*2] = rgbe[2];
           scratch[x + width*3] = rgbe[3];
        }
  
        s->func(s->context, scanlineheader, 4);
  
        /* RLE each component separately */
        for (c=0; c < 4; c++) {
           unsigned char *comp = &scratch[width*c];
  
           x = 0;
           while (x < width) {
              // find first run
              r = x;
              while (r+2 < width) {
                 if (comp[r] == comp[r+1] && comp[r] == comp[r+2])
                    break;
                 ++r;
              }
              if (r+2 >= width)
                 r = width;
              // dump up to first run
              while (x < r) {
                 int len = r-x;
                 if (len > 128) len = 128;
                 stbiw__write_dump_data(s, len, &comp[x]);
                 x += len;
              }
              // if there's a run, output it
              if (r+2 < width) { // same test as what we break out of in search loop, so only true if we break'd
                 // find next byte after run
                 while (r < width && comp[r] == comp[x])
                    ++r;
                 // output run up to r
                 while (x < r) {
                    int len = r-x;
                    if (len > 127) len = 127;
                    stbiw__write_run_data(s, len, comp[x]);
                    x += len;
                 }
              }
           }
        }
     }
  }
  
  static int stbi_write_hdr_core(stbi__write_context *s, int x, int y, int comp, float *data)
  {
     if (y <= 0 || x <= 0 || data == NULL)
        return 0;
     else {
        // Each component is stored separately. Allocate scratch space for full output scanline.
        unsigned char *scratch = (unsigned char *) STBIW_MALLOC(x*4);
        int i, len;
        char buffer[128];
        char header[] = "#?RADIANCE\n# Written by stb_image_write.h\nFORMAT=32-bit_rle_rgbe\n";
        s->func(s->context, header, sizeof(header)-1);
  
  #ifdef STBI_MSC_SECURE_CRT
        len = sprintf_s(buffer, "EXPOSURE=          1.0000000000000\n\n-Y %d +X %d\n", y, x);
  #else
        len = sprintf(buffer, "EXPOSURE=          1.0000000000000\n\n-Y %d +X %d\n", y, x);
  #endif
        s->func(s->context, buffer, len);
  
        for(i=0; i < y; i++)
           stbiw__write_hdr_scanline(s, x, comp, scratch, data + comp*x*(stbi__flip_vertically_on_write ? y-1-i : i));
        STBIW_FREE(scratch);
        return 1;
     }
  }
  
  STBIWDEF int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const float *data)
  {
     stbi__write_context s;
     stbi__start_write_callbacks(&s, func, context);
     return stbi_write_hdr_core(&s, x, y, comp, (float *) data);
  }
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_hdr(char const *filename, int x, int y, int comp, const float *data)
  {
     stbi__write_context s;
     if (stbi__start_write_file(&s,filename)) {
        int r = stbi_write_hdr_core(&s, x, y, comp, (float *) data);
        stbi__end_write_file(&s);
        return r;
     } else
        return 0;
  }
  #endif // STBI_WRITE_NO_STDIO
  
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // PNG writer
  //
  
  #ifndef STBIW_ZLIB_COMPRESS
  // stretchy buffer; stbiw__sbpush() == vector<>::push_back() -- stbiw__sbcount() == vector<>::size()
  #define stbiw__sbraw(a) ((int *) (a) - 2)
  #define stbiw__sbm(a)   stbiw__sbraw(a)[0]
  #define stbiw__sbn(a)   stbiw__sbraw(a)[1]
  
  #define stbiw__sbneedgrow(a,n)  ((a)==0 || stbiw__sbn(a)+n >= stbiw__sbm(a))
  #define stbiw__sbmaybegrow(a,n) (stbiw__sbneedgrow(a,(n)) ? stbiw__sbgrow(a,n) : 0)
  #define stbiw__sbgrow(a,n)  stbiw__sbgrowf((void **) &(a), (n), sizeof(*(a)))
  
  #define stbiw__sbpush(a, v)      (stbiw__sbmaybegrow(a,1), (a)[stbiw__sbn(a)++] = (v))
  #define stbiw__sbcount(a)        ((a) ? stbiw__sbn(a) : 0)
  #define stbiw__sbfree(a)         ((a) ? STBIW_FREE(stbiw__sbraw(a)),0 : 0)
  
  static void *stbiw__sbgrowf(void **arr, int increment, int itemsize)
  {
     int m = *arr ? 2*stbiw__sbm(*arr)+increment : increment+1;
     void *p = STBIW_REALLOC_SIZED(*arr ? stbiw__sbraw(*arr) : 0, *arr ? (stbiw__sbm(*arr)*itemsize + sizeof(int)*2) : 0, itemsize * m + sizeof(int)*2);
     STBIW_ASSERT(p);
     if (p) {
        if (!*arr) ((int *) p)[1] = 0;
        *arr = (void *) ((int *) p + 2);
        stbiw__sbm(*arr) = m;
     }
     return *arr;
  }
  
  static unsigned char *stbiw__zlib_flushf(unsigned char *data, unsigned int *bitbuffer, int *bitcount)
  {
     while (*bitcount >= 8) {
        stbiw__sbpush(data, STBIW_UCHAR(*bitbuffer));
        *bitbuffer >>= 8;
        *bitcount -= 8;
     }
     return data;
  }
  
  static int stbiw__zlib_bitrev(int code, int codebits)
  {
     int res=0;
     while (codebits--) {
        res = (res << 1) | (code & 1);
        code >>= 1;
     }
     return res;
  }
  
  static unsigned int stbiw__zlib_countm(unsigned char *a, unsigned char *b, int limit)
  {
     int i;
     for (i=0; i < limit && i < 258; ++i)
        if (a[i] != b[i]) break;
     return i;
  }
  
  static unsigned int stbiw__zhash(unsigned char *data)
  {
     stbiw_uint32 hash = data[0] + (data[1] << 8) + (data[2] << 16);
     hash ^= hash << 3;
     hash += hash >> 5;
     hash ^= hash << 4;
     hash += hash >> 17;
     hash ^= hash << 25;
     hash += hash >> 6;
     return hash;
  }
  
  #define stbiw__zlib_flush() (out = stbiw__zlib_flushf(out, &bitbuf, &bitcount))
  #define stbiw__zlib_add(code,codebits) \
        (bitbuf |= (code) << bitcount, bitcount += (codebits), stbiw__zlib_flush())
  #define stbiw__zlib_huffa(b,c)  stbiw__zlib_add(stbiw__zlib_bitrev(b,c),c)
  // default huffman tables
  #define stbiw__zlib_huff1(n)  stbiw__zlib_huffa(0x30 + (n), 8)
  #define stbiw__zlib_huff2(n)  stbiw__zlib_huffa(0x190 + (n)-144, 9)
  #define stbiw__zlib_huff3(n)  stbiw__zlib_huffa(0 + (n)-256,7)
  #define stbiw__zlib_huff4(n)  stbiw__zlib_huffa(0xc0 + (n)-280,8)
  #define stbiw__zlib_huff(n)  ((n) <= 143 ? stbiw__zlib_huff1(n) : (n) <= 255 ? stbiw__zlib_huff2(n) : (n) <= 279 ? stbiw__zlib_huff3(n) : stbiw__zlib_huff4(n))
  #define stbiw__zlib_huffb(n) ((n) <= 143 ? stbiw__zlib_huff1(n) : stbiw__zlib_huff2(n))
  
  #define stbiw__ZHASH   16384
  
  #endif // STBIW_ZLIB_COMPRESS
  
  STBIWDEF unsigned char * stbi_zlib_compress(unsigned char *data, int data_len, int *out_len, int quality)
  {
  #ifdef STBIW_ZLIB_COMPRESS
     // user provided a zlib compress implementation, use that
     return STBIW_ZLIB_COMPRESS(data, data_len, out_len, quality);
  #else // use builtin
     static unsigned short lengthc[] = { 3,4,5,6,7,8,9,10,11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,115,131,163,195,227,258, 259 };
     static unsigned char  lengtheb[]= { 0,0,0,0,0,0,0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,  4,  5,  5,  5,  5,  0 };
     static unsigned short distc[]   = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577, 32768 };
     static unsigned char  disteb[]  = { 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13 };
     unsigned int bitbuf=0;
     int i,j, bitcount=0;
     unsigned char *out = NULL;
     unsigned char ***hash_table = (unsigned char***) STBIW_MALLOC(stbiw__ZHASH * sizeof(char**));
     if (hash_table == NULL)
        return NULL;
     if (quality < 5) quality = 5;
  
     stbiw__sbpush(out, 0x78);   // DEFLATE 32K window
     stbiw__sbpush(out, 0x5e);   // FLEVEL = 1
     stbiw__zlib_add(1,1);  // BFINAL = 1
     stbiw__zlib_add(1,2);  // BTYPE = 1 -- fixed huffman
  
     for (i=0; i < stbiw__ZHASH; ++i)
        hash_table[i] = NULL;
  
     i=0;
     while (i < data_len-3) {
        // hash next 3 bytes of data to be compressed
        int h = stbiw__zhash(data+i)&(stbiw__ZHASH-1), best=3;
        unsigned char *bestloc = 0;
        unsigned char **hlist = hash_table[h];
        int n = stbiw__sbcount(hlist);
        for (j=0; j < n; ++j) {
           if (hlist[j]-data > i-32768) { // if entry lies within window
              int d = stbiw__zlib_countm(hlist[j], data+i, data_len-i);
              if (d >= best) best=d,bestloc=hlist[j];
           }
        }
        // when hash table entry is too long, delete half the entries
        if (hash_table[h] && stbiw__sbn(hash_table[h]) == 2*quality) {
           STBIW_MEMMOVE(hash_table[h], hash_table[h]+quality, sizeof(hash_table[h][0])*quality);
           stbiw__sbn(hash_table[h]) = quality;
        }
        stbiw__sbpush(hash_table[h],data+i);
  
        if (bestloc) {
           // "lazy matching" - check match at *next* byte, and if it's better, do cur byte as literal
           h = stbiw__zhash(data+i+1)&(stbiw__ZHASH-1);
           hlist = hash_table[h];
           n = stbiw__sbcount(hlist);
           for (j=0; j < n; ++j) {
              if (hlist[j]-data > i-32767) {
                 int e = stbiw__zlib_countm(hlist[j], data+i+1, data_len-i-1);
                 if (e > best) { // if next match is better, bail on current match
                    bestloc = NULL;
                    break;
                 }
              }
           }
        }
  
        if (bestloc) {
           int d = (int) (data+i - bestloc); // distance back
           STBIW_ASSERT(d <= 32767 && best <= 258);
           for (j=0; best > lengthc[j+1]-1; ++j);
           stbiw__zlib_huff(j+257);
           if (lengtheb[j]) stbiw__zlib_add(best - lengthc[j], lengtheb[j]);
           for (j=0; d > distc[j+1]-1; ++j);
           stbiw__zlib_add(stbiw__zlib_bitrev(j,5),5);
           if (disteb[j]) stbiw__zlib_add(d - distc[j], disteb[j]);
           i += best;
        } else {
           stbiw__zlib_huffb(data[i]);
           ++i;
        }
     }
     // write out final bytes
     for (;i < data_len; ++i)
        stbiw__zlib_huffb(data[i]);
     stbiw__zlib_huff(256); // end of block
     // pad with 0 bits to byte boundary
     while (bitcount)
        stbiw__zlib_add(0,1);
  
     for (i=0; i < stbiw__ZHASH; ++i)
        (void) stbiw__sbfree(hash_table[i]);
     STBIW_FREE(hash_table);
  
     {
        // compute adler32 on input
        unsigned int s1=1, s2=0;
        int blocklen = (int) (data_len % 5552);
        j=0;
        while (j < data_len) {
           for (i=0; i < blocklen; ++i) s1 += data[j+i], s2 += s1;
           s1 %= 65521, s2 %= 65521;
           j += blocklen;
           blocklen = 5552;
        }
        stbiw__sbpush(out, STBIW_UCHAR(s2 >> 8));
        stbiw__sbpush(out, STBIW_UCHAR(s2));
        stbiw__sbpush(out, STBIW_UCHAR(s1 >> 8));
        stbiw__sbpush(out, STBIW_UCHAR(s1));
     }
     *out_len = stbiw__sbn(out);
     // make returned pointer freeable
     STBIW_MEMMOVE(stbiw__sbraw(out), out, *out_len);
     return (unsigned char *) stbiw__sbraw(out);
  #endif // STBIW_ZLIB_COMPRESS
  }
  
  static unsigned int stbiw__crc32(unsigned char *buffer, int len)
  {
  #ifdef STBIW_CRC32
      return STBIW_CRC32(buffer, len);
  #else
     static unsigned int crc_table[256] =
     {
        0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
        0x0eDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
        0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
        0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
        0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
        0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
        0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
        0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
        0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
        0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
        0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
        0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
        0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
        0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
        0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
        0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
        0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
        0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
        0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
        0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
        0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
        0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
        0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
        0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
        0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
        0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
        0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
        0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
        0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
        0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
        0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
        0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
     };
  
     unsigned int crc = ~0u;
     int i;
     for (i=0; i < len; ++i)
        crc = (crc >> 8) ^ crc_table[buffer[i] ^ (crc & 0xff)];
     return ~crc;
  #endif
  }
  
  #define stbiw__wpng4(o,a,b,c,d) ((o)[0]=STBIW_UCHAR(a),(o)[1]=STBIW_UCHAR(b),(o)[2]=STBIW_UCHAR(c),(o)[3]=STBIW_UCHAR(d),(o)+=4)
  #define stbiw__wp32(data,v) stbiw__wpng4(data, (v)>>24,(v)>>16,(v)>>8,(v));
  #define stbiw__wptag(data,s) stbiw__wpng4(data, s[0],s[1],s[2],s[3])
  
  static void stbiw__wpcrc(unsigned char **data, int len)
  {
     unsigned int crc = stbiw__crc32(*data - len - 4, len+4);
     stbiw__wp32(*data, crc);
  }
  
  static unsigned char stbiw__paeth(int a, int b, int c)
  {
     int p = a + b - c, pa = abs(p-a), pb = abs(p-b), pc = abs(p-c);
     if (pa <= pb && pa <= pc) return STBIW_UCHAR(a);
     if (pb <= pc) return STBIW_UCHAR(b);
     return STBIW_UCHAR(c);
  }
  
  // @OPTIMIZE: provide an option that always forces left-predict or paeth predict
  static void stbiw__encode_png_line(unsigned char *pixels, int stride_bytes, int width, int height, int y, int n, int filter_type, signed char *line_buffer)
  {
     static int mapping[] = { 0,1,2,3,4 };
     static int firstmap[] = { 0,1,0,5,6 };
     int *mymap = (y != 0) ? mapping : firstmap;
     int i;
     int type = mymap[filter_type];
     unsigned char *z = pixels + stride_bytes * (stbi__flip_vertically_on_write ? height-1-y : y);
     int signed_stride = stbi__flip_vertically_on_write ? -stride_bytes : stride_bytes;
      
     if (type==0) {
        memcpy(line_buffer, z, width*n);
        return;
     }
  
     // first loop isn't optimized since it's just one pixel    
     for (i = 0; i < n; ++i) {
        switch (type) {
           case 1: line_buffer[i] = z[i]; break;
           case 2: line_buffer[i] = z[i] - z[i-signed_stride]; break;
           case 3: line_buffer[i] = z[i] - (z[i-signed_stride]>>1); break;
           case 4: line_buffer[i] = (signed char) (z[i] - stbiw__paeth(0,z[i-signed_stride],0)); break;
           case 5: line_buffer[i] = z[i]; break;
           case 6: line_buffer[i] = z[i]; break;
        }
     }
     switch (type) {
        case 1: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - z[i-n]; break;
        case 2: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - z[i-signed_stride]; break;
        case 3: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - ((z[i-n] + z[i-signed_stride])>>1); break;
        case 4: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - stbiw__paeth(z[i-n], z[i-signed_stride], z[i-signed_stride-n]); break;
        case 5: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - (z[i-n]>>1); break;
        case 6: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - stbiw__paeth(z[i-n], 0,0); break;
     }
  }
  
  STBIWDEF unsigned char *stbi_write_png_to_mem(const unsigned char *pixels, int stride_bytes, int x, int y, int n, int *out_len)
  {
     int force_filter = stbi_write_force_png_filter;
     int ctype[5] = { -1, 0, 4, 2, 6 };
     unsigned char sig[8] = { 137,80,78,71,13,10,26,10 };
     unsigned char *out,*o, *filt, *zlib;
     signed char *line_buffer;
     int j,zlen;
  
     if (stride_bytes == 0)
        stride_bytes = x * n;
  
     if (force_filter >= 5) {
        force_filter = -1;
     }
  
     filt = (unsigned char *) STBIW_MALLOC((x*n+1) * y); if (!filt) return 0;
     line_buffer = (signed char *) STBIW_MALLOC(x * n); if (!line_buffer) { STBIW_FREE(filt); return 0; }
     for (j=0; j < y; ++j) {
        int filter_type;
        if (force_filter > -1) {
           filter_type = force_filter;
           stbiw__encode_png_line((unsigned char*)(pixels), stride_bytes, x, y, j, n, force_filter, line_buffer);
        } else { // Estimate the best filter by running through all of them:
           int best_filter = 0, best_filter_val = 0x7fffffff, est, i;
           for (filter_type = 0; filter_type < 5; filter_type++) {
              stbiw__encode_png_line((unsigned char*)(pixels), stride_bytes, x, y, j, n, filter_type, line_buffer);
  
              // Estimate the entropy of the line using this filter; the less, the better.
              est = 0;
              for (i = 0; i < x*n; ++i) {
                 est += abs((signed char) line_buffer[i]);
              }
              if (est < best_filter_val) {
                 best_filter_val = est;
                 best_filter = filter_type;
              }
           }
           if (filter_type != best_filter) {  // If the last iteration already got us the best filter, don't redo it
              stbiw__encode_png_line((unsigned char*)(pixels), stride_bytes, x, y, j, n, best_filter, line_buffer);
              filter_type = best_filter;
           }
        }
        // when we get here, filter_type contains the filter type, and line_buffer contains the data
        filt[j*(x*n+1)] = (unsigned char) filter_type;
        STBIW_MEMMOVE(filt+j*(x*n+1)+1, line_buffer, x*n);
     }
     STBIW_FREE(line_buffer);
     zlib = stbi_zlib_compress(filt, y*( x*n+1), &zlen, stbi_write_png_compression_level);
     STBIW_FREE(filt);
     if (!zlib) return 0;
  
     // each tag requires 12 bytes of overhead
     out = (unsigned char *) STBIW_MALLOC(8 + 12+13 + 12+zlen + 12);
     if (!out) return 0;
     *out_len = 8 + 12+13 + 12+zlen + 12;
  
     o=out;
     STBIW_MEMMOVE(o,sig,8); o+= 8;
     stbiw__wp32(o, 13); // header length
     stbiw__wptag(o, "IHDR");
     stbiw__wp32(o, x);
     stbiw__wp32(o, y);
     *o++ = 8;
     *o++ = STBIW_UCHAR(ctype[n]);
     *o++ = 0;
     *o++ = 0;
     *o++ = 0;
     stbiw__wpcrc(&o,13);
  
     stbiw__wp32(o, zlen);
     stbiw__wptag(o, "IDAT");
     STBIW_MEMMOVE(o, zlib, zlen);
     o += zlen;
     STBIW_FREE(zlib);
     stbiw__wpcrc(&o, zlen);
  
     stbiw__wp32(o,0);
     stbiw__wptag(o, "IEND");
     stbiw__wpcrc(&o,0);
  
     STBIW_ASSERT(o == out + *out_len);
  
     return out;
  }
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_png(char const *filename, int x, int y, int comp, const void *data, int stride_bytes)
  {
     FILE *f;
     int len;
     unsigned char *png = stbi_write_png_to_mem((const unsigned char *) data, stride_bytes, x, y, comp, &len);
     if (png == NULL) return 0;
  
     f = stbiw__fopen(filename, "wb");
     if (!f) { STBIW_FREE(png); return 0; }
     fwrite(png, 1, len, f);
     fclose(f);
     STBIW_FREE(png);
     return 1;
  }
  #endif
  
  STBIWDEF int stbi_write_png_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data, int stride_bytes)
  {
     int len;
     unsigned char *png = stbi_write_png_to_mem((const unsigned char *) data, stride_bytes, x, y, comp, &len);
     if (png == NULL) return 0;
     func(context, png, len);
     STBIW_FREE(png);
     return 1;
  }
  
  
  /* ***************************************************************************
   *
   * JPEG writer
   *
   * This is based on Jon Olick's jo_jpeg.cpp:
   * public domain Simple, Minimalistic JPEG writer - http://www.jonolick.com/code.html
   */
  
  static const unsigned char stbiw__jpg_ZigZag[] = { 0,1,5,6,14,15,27,28,2,4,7,13,16,26,29,42,3,8,12,17,25,30,41,43,9,11,18,
        24,31,40,44,53,10,19,23,32,39,45,52,54,20,22,33,38,46,51,55,60,21,34,37,47,50,56,59,61,35,36,48,49,57,58,62,63 };
  
  static void stbiw__jpg_writeBits(stbi__write_context *s, int *bitBufP, int *bitCntP, const unsigned short *bs) {
     int bitBuf = *bitBufP, bitCnt = *bitCntP;
     bitCnt += bs[1];
     bitBuf |= bs[0] << (24 - bitCnt);
     while(bitCnt >= 8) {
        unsigned char c = (bitBuf >> 16) & 255;
        stbiw__putc(s, c);
        if(c == 255) {
           stbiw__putc(s, 0);
        }
        bitBuf <<= 8;
        bitCnt -= 8;
     }
     *bitBufP = bitBuf;
     *bitCntP = bitCnt;
  }
  
  static void stbiw__jpg_DCT(float *d0p, float *d1p, float *d2p, float *d3p, float *d4p, float *d5p, float *d6p, float *d7p) {
     float d0 = *d0p, d1 = *d1p, d2 = *d2p, d3 = *d3p, d4 = *d4p, d5 = *d5p, d6 = *d6p, d7 = *d7p;
     float z1, z2, z3, z4, z5, z11, z13;
  
     float tmp0 = d0 + d7;
     float tmp7 = d0 - d7;
     float tmp1 = d1 + d6;
     float tmp6 = d1 - d6;
     float tmp2 = d2 + d5;
     float tmp5 = d2 - d5;
     float tmp3 = d3 + d4;
     float tmp4 = d3 - d4;
  
     // Even part
     float tmp10 = tmp0 + tmp3;   // phase 2
     float tmp13 = tmp0 - tmp3;
     float tmp11 = tmp1 + tmp2;
     float tmp12 = tmp1 - tmp2;
  
     d0 = tmp10 + tmp11;       // phase 3
     d4 = tmp10 - tmp11;
  
     z1 = (tmp12 + tmp13) * 0.707106781f; // c4
     d2 = tmp13 + z1;       // phase 5
     d6 = tmp13 - z1;
  
     // Odd part
     tmp10 = tmp4 + tmp5;       // phase 2
     tmp11 = tmp5 + tmp6;
     tmp12 = tmp6 + tmp7;
  
     // The rotator is modified from fig 4-8 to avoid extra negations.
     z5 = (tmp10 - tmp12) * 0.382683433f; // c6
     z2 = tmp10 * 0.541196100f + z5; // c2-c6
     z4 = tmp12 * 1.306562965f + z5; // c2+c6
     z3 = tmp11 * 0.707106781f; // c4
  
     z11 = tmp7 + z3;      // phase 5
     z13 = tmp7 - z3;
  
     *d5p = z13 + z2;         // phase 6
     *d3p = z13 - z2;
     *d1p = z11 + z4;
     *d7p = z11 - z4;
  
     *d0p = d0;  *d2p = d2;  *d4p = d4;  *d6p = d6;
  }
  
  static void stbiw__jpg_calcBits(int val, unsigned short bits[2]) {
     int tmp1 = val < 0 ? -val : val;
     val = val < 0 ? val-1 : val;
     bits[1] = 1;
     while(tmp1 >>= 1) {
        ++bits[1];
     }
     bits[0] = val & ((1<<bits[1])-1);
  }
  
  static int stbiw__jpg_processDU(stbi__write_context *s, int *bitBuf, int *bitCnt, float *CDU, float *fdtbl, int DC, const unsigned short HTDC[256][2], const unsigned short HTAC[256][2]) {
     const unsigned short EOB[2] = { HTAC[0x00][0], HTAC[0x00][1] };
     const unsigned short M16zeroes[2] = { HTAC[0xF0][0], HTAC[0xF0][1] };
     int dataOff, i, diff, end0pos;
     int DU[64];
  
     // DCT rows
     for(dataOff=0; dataOff<64; dataOff+=8) {
        stbiw__jpg_DCT(&CDU[dataOff], &CDU[dataOff+1], &CDU[dataOff+2], &CDU[dataOff+3], &CDU[dataOff+4], &CDU[dataOff+5], &CDU[dataOff+6], &CDU[dataOff+7]);
     }
     // DCT columns
     for(dataOff=0; dataOff<8; ++dataOff) {
        stbiw__jpg_DCT(&CDU[dataOff], &CDU[dataOff+8], &CDU[dataOff+16], &CDU[dataOff+24], &CDU[dataOff+32], &CDU[dataOff+40], &CDU[dataOff+48], &CDU[dataOff+56]);
     }
     // Quantize/descale/zigzag the coefficients
     for(i=0; i<64; ++i) {
        float v = CDU[i]*fdtbl[i];
        // DU[stbiw__jpg_ZigZag[i]] = (int)(v < 0 ? ceilf(v - 0.5f) : floorf(v + 0.5f));
        // ceilf() and floorf() are C99, not C89, but I /think/ they're not needed here anyway?
        DU[stbiw__jpg_ZigZag[i]] = (int)(v < 0 ? v - 0.5f : v + 0.5f);
     }
  
     // Encode DC
     diff = DU[0] - DC;
     if (diff == 0) {
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, HTDC[0]);
     } else {
        unsigned short bits[2];
        stbiw__jpg_calcBits(diff, bits);
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, HTDC[bits[1]]);
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, bits);
     }
     // Encode ACs
     end0pos = 63;
     for(; (end0pos>0)&&(DU[end0pos]==0); --end0pos) {
     }
     // end0pos = first element in reverse order !=0
     if(end0pos == 0) {
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, EOB);
        return DU[0];
     }
     for(i = 1; i <= end0pos; ++i) {
        int startpos = i;
        int nrzeroes;
        unsigned short bits[2];
        for (; DU[i]==0 && i<=end0pos; ++i) {
        }
        nrzeroes = i-startpos;
        if ( nrzeroes >= 16 ) {
           int lng = nrzeroes>>4;
           int nrmarker;
           for (nrmarker=1; nrmarker <= lng; ++nrmarker)
              stbiw__jpg_writeBits(s, bitBuf, bitCnt, M16zeroes);
           nrzeroes &= 15;
        }
        stbiw__jpg_calcBits(DU[i], bits);
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, HTAC[(nrzeroes<<4)+bits[1]]);
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, bits);
     }
     if(end0pos != 63) {
        stbiw__jpg_writeBits(s, bitBuf, bitCnt, EOB);
     }
     return DU[0];
  }
  
  static int stbi_write_jpg_core(stbi__write_context *s, int width, int height, int comp, const void* data, int quality) {
     // Constants that don't pollute global namespace
     static const unsigned char std_dc_luminance_nrcodes[] = {0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0};
     static const unsigned char std_dc_luminance_values[] = {0,1,2,3,4,5,6,7,8,9,10,11};
     static const unsigned char std_ac_luminance_nrcodes[] = {0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d};
     static const unsigned char std_ac_luminance_values[] = {
        0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08,
        0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0,0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16,0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28,
        0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,
        0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
        0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,
        0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2,
        0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa
     };
     static const unsigned char std_dc_chrominance_nrcodes[] = {0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0};
     static const unsigned char std_dc_chrominance_values[] = {0,1,2,3,4,5,6,7,8,9,10,11};
     static const unsigned char std_ac_chrominance_nrcodes[] = {0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77};
     static const unsigned char std_ac_chrominance_values[] = {
        0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,
        0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0,0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34,0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26,
        0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,
        0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87,
        0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,
        0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,
        0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa
     };
     // Huffman tables
     static const unsigned short YDC_HT[256][2] = { {0,2},{2,3},{3,3},{4,3},{5,3},{6,3},{14,4},{30,5},{62,6},{126,7},{254,8},{510,9}};
     static const unsigned short UVDC_HT[256][2] = { {0,2},{1,2},{2,2},{6,3},{14,4},{30,5},{62,6},{126,7},{254,8},{510,9},{1022,10},{2046,11}};
     static const unsigned short YAC_HT[256][2] = {
        {10,4},{0,2},{1,2},{4,3},{11,4},{26,5},{120,7},{248,8},{1014,10},{65410,16},{65411,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {12,4},{27,5},{121,7},{502,9},{2038,11},{65412,16},{65413,16},{65414,16},{65415,16},{65416,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {28,5},{249,8},{1015,10},{4084,12},{65417,16},{65418,16},{65419,16},{65420,16},{65421,16},{65422,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {58,6},{503,9},{4085,12},{65423,16},{65424,16},{65425,16},{65426,16},{65427,16},{65428,16},{65429,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {59,6},{1016,10},{65430,16},{65431,16},{65432,16},{65433,16},{65434,16},{65435,16},{65436,16},{65437,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {122,7},{2039,11},{65438,16},{65439,16},{65440,16},{65441,16},{65442,16},{65443,16},{65444,16},{65445,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {123,7},{4086,12},{65446,16},{65447,16},{65448,16},{65449,16},{65450,16},{65451,16},{65452,16},{65453,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {250,8},{4087,12},{65454,16},{65455,16},{65456,16},{65457,16},{65458,16},{65459,16},{65460,16},{65461,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {504,9},{32704,15},{65462,16},{65463,16},{65464,16},{65465,16},{65466,16},{65467,16},{65468,16},{65469,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {505,9},{65470,16},{65471,16},{65472,16},{65473,16},{65474,16},{65475,16},{65476,16},{65477,16},{65478,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {506,9},{65479,16},{65480,16},{65481,16},{65482,16},{65483,16},{65484,16},{65485,16},{65486,16},{65487,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {1017,10},{65488,16},{65489,16},{65490,16},{65491,16},{65492,16},{65493,16},{65494,16},{65495,16},{65496,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {1018,10},{65497,16},{65498,16},{65499,16},{65500,16},{65501,16},{65502,16},{65503,16},{65504,16},{65505,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {2040,11},{65506,16},{65507,16},{65508,16},{65509,16},{65510,16},{65511,16},{65512,16},{65513,16},{65514,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {65515,16},{65516,16},{65517,16},{65518,16},{65519,16},{65520,16},{65521,16},{65522,16},{65523,16},{65524,16},{0,0},{0,0},{0,0},{0,0},{0,0},
        {2041,11},{65525,16},{65526,16},{65527,16},{65528,16},{65529,16},{65530,16},{65531,16},{65532,16},{65533,16},{65534,16},{0,0},{0,0},{0,0},{0,0},{0,0}
     };
     static const unsigned short UVAC_HT[256][2] = {
        {0,2},{1,2},{4,3},{10,4},{24,5},{25,5},{56,6},{120,7},{500,9},{1014,10},{4084,12},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {11,4},{57,6},{246,8},{501,9},{2038,11},{4085,12},{65416,16},{65417,16},{65418,16},{65419,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {26,5},{247,8},{1015,10},{4086,12},{32706,15},{65420,16},{65421,16},{65422,16},{65423,16},{65424,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {27,5},{248,8},{1016,10},{4087,12},{65425,16},{65426,16},{65427,16},{65428,16},{65429,16},{65430,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {58,6},{502,9},{65431,16},{65432,16},{65433,16},{65434,16},{65435,16},{65436,16},{65437,16},{65438,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {59,6},{1017,10},{65439,16},{65440,16},{65441,16},{65442,16},{65443,16},{65444,16},{65445,16},{65446,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {121,7},{2039,11},{65447,16},{65448,16},{65449,16},{65450,16},{65451,16},{65452,16},{65453,16},{65454,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {122,7},{2040,11},{65455,16},{65456,16},{65457,16},{65458,16},{65459,16},{65460,16},{65461,16},{65462,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {249,8},{65463,16},{65464,16},{65465,16},{65466,16},{65467,16},{65468,16},{65469,16},{65470,16},{65471,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {503,9},{65472,16},{65473,16},{65474,16},{65475,16},{65476,16},{65477,16},{65478,16},{65479,16},{65480,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {504,9},{65481,16},{65482,16},{65483,16},{65484,16},{65485,16},{65486,16},{65487,16},{65488,16},{65489,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {505,9},{65490,16},{65491,16},{65492,16},{65493,16},{65494,16},{65495,16},{65496,16},{65497,16},{65498,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {506,9},{65499,16},{65500,16},{65501,16},{65502,16},{65503,16},{65504,16},{65505,16},{65506,16},{65507,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {2041,11},{65508,16},{65509,16},{65510,16},{65511,16},{65512,16},{65513,16},{65514,16},{65515,16},{65516,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
        {16352,14},{65517,16},{65518,16},{65519,16},{65520,16},{65521,16},{65522,16},{65523,16},{65524,16},{65525,16},{0,0},{0,0},{0,0},{0,0},{0,0},
        {1018,10},{32707,15},{65526,16},{65527,16},{65528,16},{65529,16},{65530,16},{65531,16},{65532,16},{65533,16},{65534,16},{0,0},{0,0},{0,0},{0,0},{0,0}
     };
     static const int YQT[] = {16,11,10,16,24,40,51,61,12,12,14,19,26,58,60,55,14,13,16,24,40,57,69,56,14,17,22,29,51,87,80,62,18,22,
                               37,56,68,109,103,77,24,35,55,64,81,104,113,92,49,64,78,87,103,121,120,101,72,92,95,98,112,100,103,99};
     static const int UVQT[] = {17,18,24,47,99,99,99,99,18,21,26,66,99,99,99,99,24,26,56,99,99,99,99,99,47,66,99,99,99,99,99,99,
                                99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99};
     static const float aasf[] = { 1.0f * 2.828427125f, 1.387039845f * 2.828427125f, 1.306562965f * 2.828427125f, 1.175875602f * 2.828427125f, 
                                   1.0f * 2.828427125f, 0.785694958f * 2.828427125f, 0.541196100f * 2.828427125f, 0.275899379f * 2.828427125f };
  
     int row, col, i, k;
     float fdtbl_Y[64], fdtbl_UV[64];
     unsigned char YTable[64], UVTable[64];
  
     if(!data || !width || !height || comp > 4 || comp < 1) {
        return 0;
     }
  
     quality = quality ? quality : 90;
     quality = quality < 1 ? 1 : quality > 100 ? 100 : quality;
     quality = quality < 50 ? 5000 / quality : 200 - quality * 2;
  
     for(i = 0; i < 64; ++i) {
        int uvti, yti = (YQT[i]*quality+50)/100;
        YTable[stbiw__jpg_ZigZag[i]] = (unsigned char) (yti < 1 ? 1 : yti > 255 ? 255 : yti);
        uvti = (UVQT[i]*quality+50)/100;
        UVTable[stbiw__jpg_ZigZag[i]] = (unsigned char) (uvti < 1 ? 1 : uvti > 255 ? 255 : uvti);
     }
  
     for(row = 0, k = 0; row < 8; ++row) {
        for(col = 0; col < 8; ++col, ++k) {
           fdtbl_Y[k]  = 1 / (YTable [stbiw__jpg_ZigZag[k]] * aasf[row] * aasf[col]);
           fdtbl_UV[k] = 1 / (UVTable[stbiw__jpg_ZigZag[k]] * aasf[row] * aasf[col]);
        }
     }
  
     // Write Headers
     {
        static const unsigned char head0[] = { 0xFF,0xD8,0xFF,0xE0,0,0x10,'J','F','I','F',0,1,1,0,0,1,0,1,0,0,0xFF,0xDB,0,0x84,0 };
        static const unsigned char head2[] = { 0xFF,0xDA,0,0xC,3,1,0,2,0x11,3,0x11,0,0x3F,0 };
        const unsigned char head1[] = { 0xFF,0xC0,0,0x11,8,(unsigned char)(height>>8),STBIW_UCHAR(height),(unsigned char)(width>>8),STBIW_UCHAR(width),
                                        3,1,0x11,0,2,0x11,1,3,0x11,1,0xFF,0xC4,0x01,0xA2,0 };
        s->func(s->context, (void*)head0, sizeof(head0));
        s->func(s->context, (void*)YTable, sizeof(YTable));
        stbiw__putc(s, 1);
        s->func(s->context, UVTable, sizeof(UVTable));
        s->func(s->context, (void*)head1, sizeof(head1));
        s->func(s->context, (void*)(std_dc_luminance_nrcodes+1), sizeof(std_dc_luminance_nrcodes)-1);
        s->func(s->context, (void*)std_dc_luminance_values, sizeof(std_dc_luminance_values));
        stbiw__putc(s, 0x10); // HTYACinfo
        s->func(s->context, (void*)(std_ac_luminance_nrcodes+1), sizeof(std_ac_luminance_nrcodes)-1);
        s->func(s->context, (void*)std_ac_luminance_values, sizeof(std_ac_luminance_values));
        stbiw__putc(s, 1); // HTUDCinfo
        s->func(s->context, (void*)(std_dc_chrominance_nrcodes+1), sizeof(std_dc_chrominance_nrcodes)-1);
        s->func(s->context, (void*)std_dc_chrominance_values, sizeof(std_dc_chrominance_values));
        stbiw__putc(s, 0x11); // HTUACinfo
        s->func(s->context, (void*)(std_ac_chrominance_nrcodes+1), sizeof(std_ac_chrominance_nrcodes)-1);
        s->func(s->context, (void*)std_ac_chrominance_values, sizeof(std_ac_chrominance_values));
        s->func(s->context, (void*)head2, sizeof(head2));
     }
  
     // Encode 8x8 macroblocks
     {
        static const unsigned short fillBits[] = {0x7F, 7};
        const unsigned char *imageData = (const unsigned char *)data;
        int DCY=0, DCU=0, DCV=0;
        int bitBuf=0, bitCnt=0;
        // comp == 2 is grey+alpha (alpha is ignored)
        int ofsG = comp > 2 ? 1 : 0, ofsB = comp > 2 ? 2 : 0;
        int x, y, pos;
        for(y = 0; y < height; y += 8) {
           for(x = 0; x < width; x += 8) {
              float YDU[64], UDU[64], VDU[64];
              for(row = y, pos = 0; row < y+8; ++row) {
                 // row >= height => use last input row
                 int clamped_row = (row < height) ? row : height - 1;
                 int base_p = (stbi__flip_vertically_on_write ? (height-1-clamped_row) : clamped_row)*width*comp;
                 for(col = x; col < x+8; ++col, ++pos) {
                    float r, g, b;
                    // if col >= width => use pixel from last input column
                    int p = base_p + ((col < width) ? col : (width-1))*comp;
  
                    r = imageData[p+0];
                    g = imageData[p+ofsG];
                    b = imageData[p+ofsB];
                    YDU[pos]=+0.29900f*r+0.58700f*g+0.11400f*b-128;
                    UDU[pos]=-0.16874f*r-0.33126f*g+0.50000f*b;
                    VDU[pos]=+0.50000f*r-0.41869f*g-0.08131f*b;
                 }
              }
  
              DCY = stbiw__jpg_processDU(s, &bitBuf, &bitCnt, YDU, fdtbl_Y, DCY, YDC_HT, YAC_HT);
              DCU = stbiw__jpg_processDU(s, &bitBuf, &bitCnt, UDU, fdtbl_UV, DCU, UVDC_HT, UVAC_HT);
              DCV = stbiw__jpg_processDU(s, &bitBuf, &bitCnt, VDU, fdtbl_UV, DCV, UVDC_HT, UVAC_HT);
           }
        }
  
        // Do the bit alignment of the EOI marker
        stbiw__jpg_writeBits(s, &bitBuf, &bitCnt, fillBits);
     }
  
     // EOI
     stbiw__putc(s, 0xFF);
     stbiw__putc(s, 0xD9);
  
     return 1;
  }
  
  STBIWDEF int stbi_write_jpg_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data, int quality)
  {
     stbi__write_context s;
     stbi__start_write_callbacks(&s, func, context);
     return stbi_write_jpg_core(&s, x, y, comp, (void *) data, quality);
  }
  
  
  #ifndef STBI_WRITE_NO_STDIO
  STBIWDEF int stbi_write_jpg(char const *filename, int x, int y, int comp, const void *data, int quality)
  {
     stbi__write_context s;
     if (stbi__start_write_file(&s,filename)) {
        int r = stbi_write_jpg_core(&s, x, y, comp, data, quality);
        stbi__end_write_file(&s);
        return r;
     } else
        return 0;
  }
  #endif
  
  #pragma warning(pop)
  
  #endif // STB_IMAGE_WRITE_IMPLEMENTATION
  
  /* Revision history
        1.10  (2019-02-07)
               support utf8 filenames in Windows; fix warnings and platform ifdefs 
        1.09  (2018-02-11)
               fix typo in zlib quality API, improve STB_I_W_STATIC in C++
        1.08  (2018-01-29)
               add stbi__flip_vertically_on_write, external zlib, zlib quality, choose PNG filter
        1.07  (2017-07-24)
               doc fix
        1.06 (2017-07-23)
               writing JPEG (using Jon Olick's code)
        1.05   ???
        1.04 (2017-03-03)
               monochrome BMP expansion
        1.03   ???
        1.02 (2016-04-02)
               avoid allocating large structures on the stack
        1.01 (2016-01-16)
               STBIW_REALLOC_SIZED: support allocators with no realloc support
               avoid race-condition in crc initialization
               minor compile issues
        1.00 (2015-09-14)
               installable file IO function
        0.99 (2015-09-13)
               warning fixes; TGA rle support
        0.98 (2015-04-08)
               added STBIW_MALLOC, STBIW_ASSERT etc
        0.97 (2015-01-18)
               fixed HDR asserts, rewrote HDR rle logic
        0.96 (2015-01-17)
               add HDR output
               fix monochrome BMP
        0.95 (2014-08-17)
  		       add monochrome TGA output
        0.94 (2014-05-31)
               rename private functions to avoid conflicts with stb_image.h
        0.93 (2014-05-27)
               warning fixes
        0.92 (2010-08-01)
               casts to unsigned char to fix warnings
        0.91 (2010-07-17)
               first public release
        0.90   first internal release
  */
  
  /*
  ------------------------------------------------------------------------------
  This software is available under 2 licenses -- choose whichever you prefer.
  ------------------------------------------------------------------------------
  ALTERNATIVE A - MIT License
  Copyright (c) 2017 Sean Barrett
  Permission is hereby granted, free of charge, to any person obtaining a copy of 
  this software and associated documentation files (the "Software"), to deal in 
  the Software without restriction, including without limitation the rights to 
  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
  of the Software, and to permit persons to whom the Software is furnished to do 
  so, subject to the following conditions:
  The above copyright notice and this permission notice shall be included in all 
  copies or substantial portions of the Software.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
  SOFTWARE.
  ------------------------------------------------------------------------------
  ALTERNATIVE B - Public Domain (www.unlicense.org)
  This is free and unencumbered software released into the public domain.
  Anyone is free to copy, modify, publish, use, compile, sell, or distribute this 
  software, either in source code form or as a compiled binary, for any purpose, 
  commercial or non-commercial, and by any means.
  In jurisdictions that recognize copyright laws, the author or authors of this 
  software dedicate any and all copyright interest in the software to the public 
  domain. We make this dedication for the benefit of the public at large and to 
  the detriment of our heirs and successors. We intend this dedication to be an 
  overt act of relinquishment in perpetuity of all present and future rights to 
  this software under copyright law.
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
  AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  ------------------------------------------------------------------------------
  */
  