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.
33 * These functions are intended to find images with similar color content. For
34 * example when an image was saved at different compression levels or dimensions
35 * (scaled down/up) the contents are similar, but these files do not match by file
36 * size, dimensions, or checksum.
38 * These functions create a 32 x 32 array for each color channel (red, green, blue).
39 * The array represents the average color of each corresponding part of the
40 * image. (imagine the image cut into 1024 rectangles, or a 32 x 32 grid.
41 * Each grid is then processed for the average color value, this is what
42 * is stored in the array)
44 * To compare two images, generate a ImageSimilarityData for each image, then
45 * pass them to the compare function. The return value is the percent match
46 * of the two images. (for this, simple comparisons are used, basically the return
47 * is an average of the corresponding array differences)
49 * for image_sim_compare(), the return is 0.0 to 1.0: \n
50 * 1.0 for exact matches (an image is compared to itself) \n
51 * 0.0 for exact opposite images (compare an all black to an all white image) \n
52 * generally only a match of > 0.85 are significant at all, and >.95 is useful to
53 * find images that have been re-saved to other formats, dimensions, or compression.
59 using ImageSimilarityCheckAbort = std::function<bool(gdouble)>;
62 * 4 rotations (0, 90, 180, 270) combined with two mirrors (0, H)
63 * generate all possible isometric transformations
65 * = change dir of x, change dir of y, exchange x and y = 2^3 = 8
67 gdouble image_sim_data_compare_transfo(const ImageSimilarityData *a, const ImageSimilarityData *b, gchar transfo, const ImageSimilarityCheckAbort &check_abort)
69 if (!a || !b || !a->filled || !b->filled) return 0.0;
77 if (transfo & 1) { i = &j2; j = &i2; } else { i = &i2; j = &j2; }
78 for (gint j1 = 0; j1 < 32; j1++)
80 if (transfo & 2) *j = 31-j1; else *j = j1;
81 for (gint i1 = 0; i1 < 32; i1++)
83 if (transfo & 4) *i = 31-i1; else *i = i1;
84 sim += abs(a->avg_r[i1*32+j1] - b->avg_r[i2*32+j2]);
85 sim += abs(a->avg_g[i1*32+j1] - b->avg_g[i2*32+j2]);
86 sim += abs(a->avg_b[i1*32+j1] - b->avg_b[i2*32+j2]);
87 /* check for abort, if so return 0.0 */
88 if (check_abort(sim)) return 0.0;
92 return 1.0 - (static_cast<gdouble>(sim) / (255.0 * 1024.0 * 3.0));
95 gdouble image_sim_data_compare(const ImageSimilarityData *a, const ImageSimilarityData *b, const ImageSimilarityCheckAbort &check_abort)
97 gchar max_t = (options->rot_invariant_sim ? 8 : 1);
98 gdouble max_score = 0;
100 for (gchar t = 0; t < max_t; t++)
102 max_score = std::max(image_sim_data_compare_transfo(a, b, t, check_abort), max_score);
110 ImageSimilarityData *image_sim_new()
112 auto sd = g_new0(ImageSimilarityData, 1);
117 void image_sim_free(ImageSimilarityData *sd)
122 static gint image_sim_channel_eq_sort_cb(gconstpointer a, gconstpointer b)
124 auto pa = static_cast<const gint *>(a);
125 auto pb = static_cast<const gint *>(b);
126 if (pa[1] < pb[1]) return -1;
127 if (pa[1] > pb[1]) return 1;
131 static void image_sim_channel_equal(guint8 *pix, gint len)
137 buf = g_new0(gint, len * 2);
140 for (i = 0; i < len; i++)
144 buf[p] = static_cast<gint>(pix[i]);
148 qsort(buf, len, sizeof(gint) * 2, image_sim_channel_eq_sort_cb);
151 for (i = 0; i < len; i++)
157 pix[n] = static_cast<guint8>(255 * i / len);
163 static void image_sim_channel_norm(guint8 *pix, gint len)
173 for (i = 0; i < len; i++)
175 if (pix[i] < l) l = pix[i];
176 if (pix[i] > h) h = pix[i];
180 scale = (delta != 0) ? 255.0 / static_cast<gdouble>(delta) : 1.0;
182 for (i = 0; i < len; i++)
184 pix[i] = static_cast<guint8>(static_cast<gdouble>(pix[i] - l) * scale);
189 * The Alternate algorithm is only for testing of new techniques to
190 * improve the result, and hopes to reduce false positives.
192 void image_sim_alternate_processing(ImageSimilarityData *sd)
196 if (!options->alternate_similarity_algorithm.enabled)
201 image_sim_channel_norm(sd->avg_r, sizeof(sd->avg_r));
202 image_sim_channel_norm(sd->avg_g, sizeof(sd->avg_g));
203 image_sim_channel_norm(sd->avg_b, sizeof(sd->avg_b));
205 image_sim_channel_equal(sd->avg_r, sizeof(sd->avg_r));
206 image_sim_channel_equal(sd->avg_g, sizeof(sd->avg_g));
207 image_sim_channel_equal(sd->avg_b, sizeof(sd->avg_b));
209 if (options->alternate_similarity_algorithm.grayscale)
211 for (i = 0; i < (gint)sizeof(sd->avg_r); i++)
215 n = (guint8)((gint)(sd->avg_r[i] + sd->avg_g[i] + sd->avg_b[i]) / 3);
216 sd->avg_r[i] = sd->avg_g[i] = sd->avg_b[i] = n;
221 gint mround(gdouble x)
224 gdouble fpart = x-ipart;
225 return (fpart < 0.5 ? ipart : ipart+1);
228 void image_sim_fill_data(ImageSimilarityData *sd, GdkPixbuf *pixbuf)
248 gboolean x_small = FALSE; /* if less than 32 w or h, set TRUE */
249 gboolean y_small = FALSE;
250 if (!sd || !pixbuf) return;
252 w = gdk_pixbuf_get_width(pixbuf);
253 h = gdk_pixbuf_get_height(pixbuf);
254 rs = gdk_pixbuf_get_rowstride(pixbuf);
255 pix = gdk_pixbuf_get_pixels(pixbuf);
256 has_alpha = gdk_pixbuf_get_has_alpha(pixbuf);
258 p_step = has_alpha ? 4 : 3;
278 for (ys = 0; ys < 32; ys++)
280 if (y_small) j = static_cast<gdouble>(h) / 32 * ys;
281 else y_inc = mround(static_cast<gdouble>(h_left)/(32-ys));
285 for (xs = 0; xs < 32; xs++)
295 if (x_small) i = static_cast<gdouble>(w) / 32 * xs;
296 else x_inc = mround(static_cast<gdouble>(w_left)/(32-xs));
297 xy_inc = x_inc * y_inc;
299 xpos = pix + (i * p_step);
301 for (y = j; y < j + y_inc; y++)
304 for (x = i; x < i + x_inc; x++)
333 ImageSimilarityData *image_sim_new_from_pixbuf(GdkPixbuf *pixbuf)
335 ImageSimilarityData *sd;
337 sd = image_sim_new();
338 image_sim_fill_data(sd, pixbuf);
343 static gdouble alternate_image_sim_compare_fast(const ImageSimilarityData *a, const ImageSimilarityData *b, gdouble min)
350 if (!a || !b || !a->filled || !b->filled) return 0.0;
355 for (j = 0; j < 1024; j += 32)
357 for (i = j; i < j + 32; i++)
364 cr = abs(a->avg_r[i] - b->avg_r[i]);
365 cg = abs(a->avg_g[i] - b->avg_g[i]);
366 cb = abs(a->avg_b[i] - b->avg_b[i]);
369 sim += cd + abs(cd - ld);
372 /* check for abort, if so return 0.0 */
373 if ((gdouble)sim / (255.0 * 1024.0 * 4.0) > min) return 0.0;
376 return (1.0 - ((gdouble)sim / (255.0 * 1024.0 * 4.0)) );
379 gdouble image_sim_compare(ImageSimilarityData *a, ImageSimilarityData *b)
381 return image_sim_data_compare(a, b, [](gdouble){ return false; });
384 /* this uses a cutoff point so that it can abort early when it gets to
385 * a point that can simply no longer make the cut-off point.
387 gdouble image_sim_compare_fast(ImageSimilarityData *a, ImageSimilarityData *b, gdouble min)
391 if (options->alternate_similarity_algorithm.enabled)
393 return alternate_image_sim_compare_fast(a, b, min);
396 return image_sim_data_compare(a, b, [min](gdouble sim){ return (sim / (255.0 * 1024.0 * 3.0)) > min; });
398 /* vim: set shiftwidth=8 softtabstop=0 cindent cinoptions={1s: */