2 * Copyright (C) 2004 John Ellis
3 * Copyright (C) 2008 - 2016 The Geeqie Team
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
29 * These functions are intended to find images with similar color content. For
30 * example when an image was saved at different compression levels or dimensions
31 * (scaled down/up) the contents are similar, but these files do not match by file
32 * size, dimensions, or checksum.
34 * These functions create a 32 x 32 array for each color channel (red, green, blue).
35 * The array represents the average color of each corresponding part of the
36 * image. (imagine the image cut into 1024 rectangles, or a 32 x 32 grid.
37 * Each grid is then processed for the average color value, this is what
38 * is stored in the array)
40 * To compare two images, generate a ImageSimilarityData for each image, then
41 * pass them to the compare function. The return value is the percent match
42 * of the two images. (for this, simple comparisons are used, basically the return
43 * is an average of the corresponding array differences)
45 * for image_sim_compare(), the return is 0.0 to 1.0: \n
46 * 1.0 for exact matches (an image is compared to itself) \n
47 * 0.0 for exact opposite images (compare an all black to an all white image) \n
48 * generally only a match of > 0.85 are significant at all, and >.95 is useful to
49 * find images that have been re-saved to other formats, dimensions, or compression.
54 * The experimental (alternate) algorithm is only for testing of new techniques to
55 * improve the result, and hopes to reduce false positives.
58 static gboolean alternate_enabled = FALSE;
60 void image_sim_alternate_set(gboolean enable)
62 alternate_enabled = enable;
65 gboolean image_sim_alternate_enabled(void)
67 return alternate_enabled;
70 ImageSimilarityData *image_sim_new(void)
72 ImageSimilarityData *sd = g_new0(ImageSimilarityData, 1);
77 void image_sim_free(ImageSimilarityData *sd)
82 static gint image_sim_channel_eq_sort_cb(gconstpointer a, gconstpointer b)
84 gint *pa = (gpointer)a;
85 gint *pb = (gpointer)b;
86 if (pa[1] < pb[1]) return -1;
87 if (pa[1] > pb[1]) return 1;
91 static void image_sim_channel_equal(guint8 *pix, gint len)
97 buf = g_new0(gint, len * 2);
100 for (i = 0; i < len; i++)
104 buf[p] = (gint)pix[i];
108 qsort(buf, len, sizeof(gint) * 2, image_sim_channel_eq_sort_cb);
111 for (i = 0; i < len; i++)
117 pix[n] = (guint8)(255 * i / len);
123 static void image_sim_channel_norm(guint8 *pix, gint len)
131 for (i = 0; i < len; i++)
133 if (pix[i] < l) l = pix[i];
134 if (pix[i] > h) h = pix[i];
138 scale = (delta != 0) ? 255.0 / (gdouble)(delta) : 1.0;
140 for (i = 0; i < len; i++)
142 pix[i] = (guint8)((gdouble)(pix[i] - l) * scale);
147 * define these to enable various components of the experimental compare functions
149 * Convert the thumbprint to greyscale (ignore all color information when comparing)
150 * #define ALTERNATE_USES_GREYSCALE 1
152 * Take into account the difference in change from one pixel to the next
153 * #define ALTERNATE_INCLUDE_COMPARE_CHANGE 1
156 void image_sim_alternate_processing(ImageSimilarityData *sd)
158 #ifdef ALTERNATE_USES_GREYSCALE
162 if (!alternate_enabled) return;
164 image_sim_channel_norm(sd->avg_r, sizeof(sd->avg_r));
165 image_sim_channel_norm(sd->avg_g, sizeof(sd->avg_g));
166 image_sim_channel_norm(sd->avg_b, sizeof(sd->avg_b));
168 image_sim_channel_equal(sd->avg_r, sizeof(sd->avg_r));
169 image_sim_channel_equal(sd->avg_g, sizeof(sd->avg_g));
170 image_sim_channel_equal(sd->avg_b, sizeof(sd->avg_b));
172 #ifdef ALTERNATE_USES_GREYSCALE
173 for (i = 0; i < sizeof(sd->avg_r); i++)
177 n = (guint8)((gint)(sd->avg_r[i] + sd->avg_g[i] + sd->avg_b[i]) / 3);
178 sd->avg_r[i] = sd->avg_g[i] = sd->avg_b[i] = n;
183 gint mround(gdouble x)
186 gdouble fpart = x-ipart;
187 return (fpart < 0.5 ? ipart : ipart+1);
190 void image_sim_fill_data(ImageSimilarityData *sd, GdkPixbuf *pixbuf)
201 gint x_inc, y_inc, xy_inc;
205 gboolean x_small = FALSE; /* if less than 32 w or h, set TRUE */
206 gboolean y_small = FALSE;
207 if (!sd || !pixbuf) return;
209 w = gdk_pixbuf_get_width(pixbuf);
210 h = gdk_pixbuf_get_height(pixbuf);
211 rs = gdk_pixbuf_get_rowstride(pixbuf);
212 pix = gdk_pixbuf_get_pixels(pixbuf);
213 has_alpha = gdk_pixbuf_get_has_alpha(pixbuf);
215 p_step = has_alpha ? 4 : 3;
235 for (ys = 0; ys < 32; ys++)
237 if (y_small) j = (gdouble)h / 32 * ys;
238 else y_inc = mround((gdouble)h_left/(32-ys));
242 for (xs = 0; xs < 32; xs++)
249 if (x_small) i = (gdouble)w / 32 * xs;
250 else x_inc = mround((gdouble)w_left/(32-xs));
251 xy_inc = x_inc * y_inc;
253 xpos = pix + (i * p_step);
255 for (y = j; y < j + y_inc; y++)
258 for (x = i; x < i + x_inc; x++)
287 ImageSimilarityData *image_sim_new_from_pixbuf(GdkPixbuf *pixbuf)
289 ImageSimilarityData *sd;
291 sd = image_sim_new();
292 image_sim_fill_data(sd, pixbuf);
297 #ifdef ALTERNATE_INCLUDE_COMPARE_CHANGE
298 static gdouble alternate_image_sim_compare_fast(ImageSimilarityData *a, ImageSimilarityData *b, gdouble min)
305 if (!a || !b || !a->filled || !b->filled) return 0.0;
311 for (j = 0; j < 1024; j += 32)
313 for (i = j; i < j + 32; i++)
318 cr = abs(a->avg_r[i] - b->avg_r[i]);
319 cg = abs(a->avg_g[i] - b->avg_g[i]);
320 cb = abs(a->avg_b[i] - b->avg_b[i]);
323 sim += cd + abs(cd - ld);
326 /* check for abort, if so return 0.0 */
327 if ((gdouble)sim / (255.0 * 1024.0 * 4.0) > min) return 0.0;
330 return (1.0 - ((gdouble)sim / (255.0 * 1024.0 * 4.0)) );
334 gdouble image_sim_compare_transfo(ImageSimilarityData *a, ImageSimilarityData *b, gchar transfo)
340 if (!a || !b || !a->filled || !b->filled) return 0.0;
344 if (transfo & 1) { i = &j2; j = &i2; } else { i = &i2; j = &j2; }
345 for (j1 = 0; j1 < 32; j1++)
347 if (transfo & 2) *j = 31-j1; else *j = j1;
348 for (i1 = 0; i1 < 32; i1++)
350 if (transfo & 4) *i = 31-i1; else *i = i1;
351 sim += abs(a->avg_r[i1*32+j1] - b->avg_r[i2*32+j2]);
352 sim += abs(a->avg_g[i1*32+j1] - b->avg_g[i2*32+j2]);
353 sim += abs(a->avg_b[i1*32+j1] - b->avg_b[i2*32+j2]);
357 return 1.0 - ((gdouble)sim / (255.0 * 1024.0 * 3.0));
360 gdouble image_sim_compare(ImageSimilarityData *a, ImageSimilarityData *b)
362 gint max_t = (options->rot_invariant_sim ? 8 : 1);
365 gdouble score, max_score = 0;
367 for(t = 0; t < max_t; t++)
369 score = image_sim_compare_transfo(a, b, t);
370 if (score > max_score) max_score = score;
377 4 rotations (0, 90, 180, 270) combined with two mirrors (0, H)
378 generate all possible isometric transformations
380 = change dir of x, change dir of y, exchange x and y = 2^3 = 8
382 gdouble image_sim_compare_fast_transfo(ImageSimilarityData *a, ImageSimilarityData *b, gdouble min, gchar transfo)
388 #ifdef ALTERNATE_INCLUDE_COMPARE_CHANGE
389 if (alternate_enabled) return alternate_image_sim_compare_fast(a, b, min);
392 if (!a || !b || !a->filled || !b->filled) return 0.0;
397 if (transfo & 1) { i = &j2; j = &i2; } else { i = &i2; j = &j2; }
398 for (j1 = 0; j1 < 32; j1++)
400 if (transfo & 2) *j = 31-j1; else *j = j1;
401 for (i1 = 0; i1 < 32; i1++)
403 if (transfo & 4) *i = 31-i1; else *i = i1;
404 sim += abs(a->avg_r[i1*32+j1] - b->avg_r[i2*32+j2]);
405 sim += abs(a->avg_g[i1*32+j1] - b->avg_g[i2*32+j2]);
406 sim += abs(a->avg_b[i1*32+j1] - b->avg_b[i2*32+j2]);
408 /* check for abort, if so return 0.0 */
409 if ((gdouble)sim / (255.0 * 1024.0 * 3.0) > min) return 0.0;
412 return (1.0 - ((gdouble)sim / (255.0 * 1024.0 * 3.0)) );
415 /* this uses a cutoff point so that it can abort early when it gets to
416 * a point that can simply no longer make the cut-off point.
418 gdouble image_sim_compare_fast(ImageSimilarityData *a, ImageSimilarityData *b, gdouble min)
420 gint max_t = (options->rot_invariant_sim ? 8 : 1);
423 gdouble score, max_score = 0;
425 for(t = 0; t < max_t; t++)
427 score = image_sim_compare_fast_transfo(a, b, min, t);
428 if (score > max_score) max_score = score;
432 /* vim: set shiftwidth=8 softtabstop=0 cindent cinoptions={1s: */