third_party/fuzzymatch/fuzzymatch.c

   1 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /* Fuzzy pixel test matching.
   6  *
   7  * This is designed to compare two layout test images (RGB 800x600) and manage
   8  * to ignore the noise caused by the font renderers choosing slightly different
   9  * pixels.
  10  *
  11  *    A             B
  12  *    |             |
  13  *    |--->delta<---|
  14  *           |
  15  *           V
  16  *          gray
  17  *           |
  18  *           V
  19  *         binary
  20  *           |
  21  *    |-------------|
  22  *    |             |
  23  *   1x3           3x1   Morphological openings
  24  *    |             |
  25  *    |-----OR------|
  26  *           |
  27  *           V
  28  *     count pixels
  29  *
  30  * The result is that three different pixels in a row (vertically or
  31  * horizontally) will cause the match to fail and the binary exits with code 1.
  32  * Otherwise the binary exists with code 0.
  33  *
  34  * This requires leptonica to be installed. On Ubuntu do
  35  *   # apt-get install libleptonica libleptonica-dev libtiff4-dev
  36  *
  37  * Build with:
  38  *   % gcc -o fuzzymatch fuzzymatch.c -llept -ljpeg -ltiff -lpng -lz -lm -Wall -O2
  39  *
  40  * Options:
  41  *   --highlight: write highlight.png which is a copy of the first image
  42  *     argument where the differing areas (after noise removal) are ringed
  43  *     in red
  44  *   --no-ignore-scrollbars: usually the rightmost 15px of the image are
  45  *     ignored to account for scrollbars. Use this flag to include them in
  46  *     consideration
  47  */
  48
  49 #include <unistd.h>
  50 #include <stdio.h>
  51 #include <leptonica/allheaders.h>
  52
  53 static int
  54 usage(const char *argv0) {
  55   fprintf(stderr, "Usage: %s [--highlight] [--no-ignore-scrollbars] "
  56                   "[--output filename] "
  57                   "<input a> <input b>\n", argv0);
  58   return 1;
  59 }
  60
  61 int
  62 main(int argc, char **argv) {
  63   if (argc < 3)
  64     return usage(argv[0]);
  65
  66   char highlight = 0;
  67   char ignore_scrollbars = 1;
  68   /* Default output filename; can be overridden by command line. */
  69   const char *output_filename = "highlight.png";
  70
  71   int argi = 1;
  72
  73   for (; argi < argc; ++argi) {
  74     if (strcmp("--highlight", argv[argi]) == 0) {
  75       highlight = 1;
  76     } else if (strcmp("--no-ignore-scrollbars", argv[argi]) == 0) {
  77       ignore_scrollbars = 0;
  78     } else if (strcmp("--output", argv[argi]) == 0) {
  79       if (argi + 1 >= argc) {
  80         fprintf(stderr, "missing argument to --output\n");
  81         return 1;
  82       }
  83       output_filename = argv[++argi];
  84     } else {
  85       break;
  86     }
  87   }
  88
  89   if (argc - argi < 2)
  90     return usage(argv[0]);
  91
  92   PIX *a = pixRead(argv[argi]);
  93   PIX *b = pixRead(argv[argi + 1]);
  94
  95   if (!a) {
  96     fprintf(stderr, "Failed to open %s\n", argv[argi]);
  97     return 1;
  98   }
  99
 100   if (!b) {
 101     fprintf(stderr, "Failed to open %s\n", argv[argi + 1]);
 102     return 1;
 103   }
 104
 105   if (pixGetWidth(a) != pixGetWidth(b) ||
 106       pixGetHeight(a) != pixGetHeight(b)) {
 107     fprintf(stderr, "Inputs are difference sizes\n");
 108     return 1;
 109   }
 110
 111   PIX *delta = pixAbsDifference(a, b);
 112   pixInvert(delta, delta);
 113   if (!highlight)
 114     pixDestroy(&a);
 115   pixDestroy(&b);
 116
 117   PIX *deltagray = pixConvertRGBToGray(delta, 0, 0, 0);
 118   pixDestroy(&delta);
 119
 120   PIX *deltabinary = pixThresholdToBinary(deltagray, 254);
 121   PIX *deltabinaryclipped;
 122   const int clipwidth = pixGetWidth(deltabinary) - 15;
 123   const int clipheight = pixGetHeight(deltabinary) - 15;
 124
 125   if (ignore_scrollbars && clipwidth > 0 && clipheight > 0) {
 126     BOX *clip = boxCreate(0, 0, clipwidth, clipheight);
 127
 128     deltabinaryclipped = pixClipRectangle(deltabinary, clip, NULL);
 129     boxDestroy(&clip);
 130     pixDestroy(&deltabinary);
 131   } else {
 132     deltabinaryclipped = deltabinary;
 133     deltabinary = NULL;
 134   }
 135
 136   PIX *hopened = pixOpenBrick(NULL, deltabinaryclipped, 3, 1);
 137   PIX *vopened = pixOpenBrick(NULL, deltabinaryclipped, 1, 3);
 138   pixDestroy(&deltabinaryclipped);
 139
 140   PIX *opened = pixOr(NULL, hopened, vopened);
 141   pixDestroy(&hopened);
 142   pixDestroy(&vopened);
 143
 144   l_int32 count;
 145   pixCountPixels(opened, &count, NULL);
 146   fprintf(stderr, "%d\n", count);
 147
 148   if (count && highlight) {
 149     PIX *d1 = pixDilateBrick(NULL, opened, 7, 7);
 150     PIX *d2 = pixDilateBrick(NULL, opened, 3, 3);
 151     pixInvert(d2, d2);
 152     pixAnd(d1, d1, d2);
 153     pixPaintThroughMask(a, d1, 0, 0, 0xff << 24);
 154     pixWrite(output_filename, a, IFF_PNG);
 155   }
 156
 157   return count > 0;
 158 }