demos/grinder/histogram.c

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2015 Cyril Hrubis <metan@ucw.cz>                       *
  20  *                                                                           *
  21  *****************************************************************************/
  22
  23 #include "histogram.h"
  24
  25 void histogram_to_png(const GP_Pixmap *src, const char *filename)
  26 {
  27         GP_Histogram *hist;
  28
  29         hist = GP_HistogramAlloc(src->pixel_type);
  30         if (!hist) {
  31                 fprintf(stderr, "Failed to allocate histogram\n");
  32                 return;
  33         }
  34
  35         GP_FilterHistogram(hist, src, NULL);
  36
  37         unsigned int i, j;
  38
  39         GP_Pixmap *res = GP_PixmapAlloc(257*4, 256, GP_PIXEL_RGB888);
  40
  41         GP_Fill(res, 0xffffff);
  42
  43         GP_HistogramChannel *hist_r = GP_HistogramChannelByName(hist, "R");
  44
  45         for (i = 0; i < hist_r->len; i++)
  46                 GP_VLineXYH(res, i, 256, -255.00 * hist_r->hist[i] / hist_r->max + 0.5 , 0xff0000);
  47
  48         GP_HistogramChannel *hist_g = GP_HistogramChannelByName(hist, "G");
  49
  50         for (i = 0; i < hist_g->len; i++)
  51                 GP_VLineXYH(res, i+257, 256, -255.00 * hist_g->hist[i] / hist_g->max + 0.5 , 0x00ff00);
  52
  53         GP_HistogramChannel *hist_b = GP_HistogramChannelByName(hist, "B");
  54
  55         for (i = 0; i < hist_b->len; i++)
  56                 GP_VLineXYH(res, i+514, 256, -255.00 * hist_b->hist[i] / hist_b->max + 0.5 , 0x0000ff);
  57
  58         uint32_t max = GP_MAX3(hist_r->max, hist_g->max, hist_b->max);
  59
  60         for (i = 0; i < hist_r->len; i++) {
  61                 for (j = 0; j < hist_r->len; j++) {
  62                         GP_Pixel pix = 0;
  63
  64                         if (255 * hist_r->hist[i] / max + 0.5 > j)
  65                                 pix |= 0xff0000;
  66
  67                         if (255 * hist_g->hist[i] / max + 0.5 > j)
  68                                 pix |= 0x00ff00;
  69
  70                         if (255 * hist_b->hist[i] / max + 0.5 > j)
  71                                 pix |= 0x0000ff;
  72
  73                         GP_PutPixel(res, i+771, 256-j, pix);
  74                 }
  75         }
  76
  77         GP_SavePNG(res, filename, NULL);
  78
  79         GP_PixmapFree(res);
  80         GP_HistogramFree(hist);
  81 }