text: ///////////////////////////////////////////////////////////////////////
  // File:        associate.cpp
  // Description: Functions for scoring segmentation paths according to
  //              their character widths, gap widths and seam cuts.
  // Author:      Daria Antonova
  // Created:     Mon Mar 8 11:26:43 PDT 2010
  //
  // (C) Copyright 2010, Google Inc.
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  // http://www.apache.org/licenses/LICENSE-2.0
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  //
  ///////////////////////////////////////////////////////////////////////
  
  #include <cmath>
  #include <cstdio>
  
  #include "associate.h"
  #include "normalis.h"
  #include "pageres.h"
  
  namespace tesseract {
  
  const float AssociateUtils::kMaxFixedPitchCharAspectRatio = 2.0f;
  const float AssociateUtils::kMinGap = 0.03f;
  
  void AssociateUtils::ComputeStats(int col, int row, const AssociateStats *parent_stats,
                                    int parent_path_length, bool fixed_pitch, float max_char_wh_ratio,
                                    WERD_RES *word_res, bool debug, AssociateStats *stats) {
    stats->Clear();
  
    ASSERT_HOST(word_res != nullptr);
    if (word_res->blob_widths.empty()) {
      return;
    }
    if (debug) {
      tprintf("AssociateUtils::ComputeStats() for col=%d, row=%d%s\n", col, row,
              fixed_pitch ? " (fixed pitch)" : "");
    }
    float normalizing_height = kBlnXHeight;
    ROW *blob_row = word_res->blob_row;
    // TODO(rays/daria) Can unicharset.script_has_xheight be useful here?
    if (fixed_pitch && blob_row != nullptr) {
      // For fixed pitch language like CJK, we use the full text height
      // as the normalizing factor so we are not dependent on xheight
      // calculation.
      if (blob_row->body_size() > 0.0f) {
        normalizing_height = word_res->denorm.y_scale() * blob_row->body_size();
      } else {
        normalizing_height =
            word_res->denorm.y_scale() * (blob_row->x_height() + blob_row->ascenders());
      }
      if (debug) {
        tprintf("normalizing height = %g (scale %g xheight %g ascenders %g)\n", normalizing_height,
                word_res->denorm.y_scale(), blob_row->x_height(), blob_row->ascenders());
      }
    }
    float wh_ratio = word_res->GetBlobsWidth(col, row) / normalizing_height;
    if (wh_ratio > max_char_wh_ratio) {
      stats->bad_shape = true;
    }
    // Compute the gap sum for this shape. If there are only negative or only
    // positive gaps, record their sum in stats->gap_sum. However, if there is
    // a mixture, record only the sum of the positive gaps.
    // TODO(antonova): explain fragment.
    int negative_gap_sum = 0;
    for (int c = col; c < row; ++c) {
      int gap = word_res->GetBlobsGap(c);
      (gap > 0) ? stats->gap_sum += gap : negative_gap_sum += gap;
    }
    if (stats->gap_sum == 0) {
      stats->gap_sum = negative_gap_sum;
    }
    if (debug) {
      tprintf("wh_ratio=%g (max_char_wh_ratio=%g) gap_sum=%d %s\n", wh_ratio, max_char_wh_ratio,
              stats->gap_sum, stats->bad_shape ? "bad_shape" : "");
    }
    // Compute shape_cost (for fixed pitch mode).
    if (fixed_pitch) {
      bool end_row = (row == (word_res->ratings->dimension() - 1));
  
      // Ensure that the blob has gaps on the left and the right sides
      // (except for beginning and ending punctuation) and that there is
      // no cutting through ink at the blob boundaries.
      if (col > 0) {
        float left_gap = word_res->GetBlobsGap(col - 1) / normalizing_height;
        SEAM *left_seam = word_res->seam_array[col - 1];
        if ((!end_row && left_gap < kMinGap) || left_seam->priority() > 0.0f) {
          stats->bad_shape = true;
        }
        if (debug) {
          tprintf("left_gap %g, left_seam %g %s\n", left_gap, left_seam->priority(),
                  stats->bad_shape ? "bad_shape" : "");
        }
      }
      float right_gap = 0.0f;
      if (!end_row) {
        right_gap = word_res->GetBlobsGap(row) / normalizing_height;
        SEAM *right_seam = word_res->seam_array[row];
        if (right_gap < kMinGap || right_seam->priority() > 0.0f) {
          stats->bad_shape = true;
          if (right_gap < kMinGap) {
            stats->bad_fixed_pitch_right_gap = true;
          }
        }
        if (debug) {
          tprintf("right_gap %g right_seam %g %s\n", right_gap, right_seam->priority(),
                  stats->bad_shape ? "bad_shape" : "");
        }
      }
  
      // Impose additional segmentation penalties if blob widths or gaps
      // distribution don't fit a fixed-pitch model.
      // Since we only know the widths and gaps of the path explored so far,
      // the means and variances are computed for the path so far (not
      // considering characters to the right of the last character on the path).
      stats->full_wh_ratio = wh_ratio + right_gap;
      if (parent_stats != nullptr) {
        stats->full_wh_ratio_total = (parent_stats->full_wh_ratio_total + stats->full_wh_ratio);
        float mean = stats->full_wh_ratio_total / static_cast<float>(parent_path_length + 1);
        stats->full_wh_ratio_var =
            parent_stats->full_wh_ratio_var + pow(mean - stats->full_wh_ratio, 2);
      } else {
        stats->full_wh_ratio_total = stats->full_wh_ratio;
      }
      if (debug) {
        tprintf("full_wh_ratio %g full_wh_ratio_total %g full_wh_ratio_var %g\n",
                stats->full_wh_ratio, stats->full_wh_ratio_total, stats->full_wh_ratio_var);
      }
  
      stats->shape_cost = FixedPitchWidthCost(wh_ratio, right_gap, end_row, max_char_wh_ratio);
  
      // For some reason Tesseract prefers to treat the whole CJ words
      // as one blob when the initial segmentation is particularly bad.
      // This hack is to avoid favoring such states.
      if (col == 0 && end_row && wh_ratio > max_char_wh_ratio) {
        stats->shape_cost += 10;
      }
      stats->shape_cost += stats->full_wh_ratio_var;
      if (debug) {
        tprintf("shape_cost %g\n", stats->shape_cost);
      }
    }
  }
  
  float AssociateUtils::FixedPitchWidthCost(float norm_width, float right_gap, bool end_pos,
                                            float max_char_wh_ratio) {
    float cost = 0.0f;
    if (norm_width > max_char_wh_ratio) {
      cost += norm_width;
    }
    if (norm_width > kMaxFixedPitchCharAspectRatio) {
      cost += norm_width * norm_width; // extra penalty for merging CJK chars
    }
    // Penalize skinny blobs, except for punctuation in the last position.
    if (norm_width + right_gap < 0.5f && !end_pos) {
      cost += 1.0f - (norm_width + right_gap);
    }
    return cost;
  }
  
  } // namespace tesseract
  