1 /**
2 * Title: Crop
3 *
4 * A couple of functions to crop images, automatically (auto detection of
5 * the borders color), using a given color (with or without tolerance)
6 * or using a selection.
7 *
8 * The threshold method works relatively well but it can be improved.
9 * Maybe L*a*b* and Delta-E will give better results (and a better
10 * granularity).
11 *
12 * Example:
13 * (start code)
14 * im2 = gdImageAutoCrop(im, GD_CROP_SIDES);
15 * if (im2) {
16
17 * }
18 * gdImageDestroy(im2);
19 * (end code)
20 **/
21
22 #include <gd.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <math.h>
26
27 static int gdGuessBackgroundColorFromCorners(gdImagePtr im, int *color);
28 static int gdColorMatch(gdImagePtr im, int col1, int col2, float threshold);
29
30 /**
31 * Function: gdImageCrop
32 * Crops the src image using the area defined by the <crop> rectangle.
33 * The result is returned as a new image.
34 *
35 *
36 * Parameters:
37 * src - Source image
38 * crop - Rectangular region to crop
39 *
40 * Returns:
41 * <gdImagePtr> on success or NULL
42 */
gdImageCrop(gdImagePtr src,const gdRectPtr crop)43 gdImagePtr gdImageCrop(gdImagePtr src, const gdRectPtr crop)
44 {
45 gdImagePtr dst;
46 int y;
47
48 /* allocate the requested size (could be only partially filled) */
49 if (src->trueColor) {
50 dst = gdImageCreateTrueColor(crop->width, crop->height);
51 if (dst == NULL) {
52 return NULL;
53 }
54 gdImageSaveAlpha(dst, 1);
55 } else {
56 dst = gdImageCreate(crop->width, crop->height);
57 if (dst == NULL) {
58 return NULL;
59 }
60 gdImagePaletteCopy(dst, src);
61 }
62 dst->transparent = src->transparent;
63
64 /* check position in the src image */
65 if (crop->x < 0 || crop->x>=src->sx || crop->y<0 || crop->y>=src->sy) {
66 return dst;
67 }
68
69 /* reduce size if needed */
70 if ((src->sx - crop->width) < crop->x) {
71 crop->width = src->sx - crop->x;
72 }
73 if ((src->sy - crop->height) < crop->y) {
74 crop->height = src->sy - crop->y;
75 }
76
77 #if 0
78 printf("rect->x: %i\nrect->y: %i\nrect->width: %i\nrect->height: %i\n", crop->x, crop->y, crop->width, crop->height);
79 #endif
80 y = crop->y;
81 if (src->trueColor) {
82 unsigned int dst_y = 0;
83 while (y < (crop->y + crop->height)) {
84 /* TODO: replace 4 w/byte per channel||pitch once available */
85 memcpy(dst->tpixels[dst_y++], src->tpixels[y++] + crop->x, crop->width * 4);
86 }
87 } else {
88 int x;
89 for (y = crop->y; y < (crop->y + crop->height); y++) {
90 for (x = crop->x; x < (crop->x + crop->width); x++) {
91 dst->pixels[y - crop->y][x - crop->x] = src->pixels[y][x];
92 }
93 }
94 }
95 return dst;
96 }
97
98 /**
99 * Function: gdImageAutoCrop
100 * Automatic croping of the src image using the given mode
101 * (see <gdCropMode>)
102 *
103 *
104 * Parameters:
105 * im - Source image
106 * mode - crop mode
107 *
108 * Returns:
109 * <gdImagePtr> on success or NULL
110 *
111 * See also:
112 * <gdCropMode>
113 */
gdImageCropAuto(gdImagePtr im,const unsigned int mode)114 gdImagePtr gdImageCropAuto(gdImagePtr im, const unsigned int mode)
115 {
116 const int width = gdImageSX(im);
117 const int height = gdImageSY(im);
118
119 int x,y;
120 int color, corners, match;
121 gdRect crop;
122
123 crop.x = 0;
124 crop.y = 0;
125 crop.width = 0;
126 crop.height = 0;
127
128 switch (mode) {
129 case GD_CROP_TRANSPARENT:
130 color = gdImageGetTransparent(im);
131 break;
132
133 case GD_CROP_BLACK:
134 color = gdImageColorClosestAlpha(im, 0, 0, 0, 0);
135 break;
136
137 case GD_CROP_WHITE:
138 color = gdImageColorClosestAlpha(im, 255, 255, 255, 0);
139 break;
140
141 case GD_CROP_SIDES:
142 corners = gdGuessBackgroundColorFromCorners(im, &color);
143 break;
144
145 case GD_CROP_DEFAULT:
146 default:
147 color = gdImageGetTransparent(im);
148 if (color == -1) {
149 corners = gdGuessBackgroundColorFromCorners(im, &color);
150 }
151 break;
152 }
153
154 /* TODO: Add gdImageGetRowPtr and works with ptr at the row level
155 * for the true color and palette images
156 * new formats will simply work with ptr
157 */
158 match = 1;
159 for (y = 0; match && y < height; y++) {
160 for (x = 0; match && x < width; x++) {
161 int c2 = gdImageGetPixel(im, x, y);
162 match = (color == c2);
163 }
164 }
165
166 /* Whole image would be cropped > bye */
167 if (match) {
168 return NULL;
169 }
170
171 crop.y = y - 1;
172
173 match = 1;
174 for (y = height - 1; match && y >= 0; y--) {
175 for (x = 0; match && x < width; x++) {
176 match = (color == gdImageGetPixel(im, x,y));
177 }
178 }
179 crop.height = y - crop.y + 2;
180
181 match = 1;
182 for (x = 0; match && x < width; x++) {
183 for (y = 0; match && y < crop.y + crop.height; y++) {
184 match = (color == gdImageGetPixel(im, x,y));
185 }
186 }
187 crop.x = x - 1;
188
189 match = 1;
190 for (x = width - 1; match && x >= 0; x--) {
191 for (y = 0; match && y < crop.y + crop.height; y++) {
192 match = (color == gdImageGetPixel(im, x,y));
193 }
194 }
195 crop.width = x - crop.x + 2;
196
197 if (crop.x < 0 || crop.y < 0 || crop.width <= 0 || crop.height <= 0) {
198 return NULL;
199 }
200 return gdImageCrop(im, &crop);
201 }
202 /*TODOs: Implement DeltaE instead, way better perceptual differences */
203 /**
204 * Function: gdImageThresholdCrop
205 * Crop an image using a given color. The threshold argument defines
206 * the tolerance to be used while comparing the image color and the
207 * color to crop. The method used to calculate the color difference
208 * is based on the color distance in the RGB(a) cube.
209 *
210 *
211 * Parameters:
212 * im - Source image
213 * color - color to crop
214 * threshold - tolerance (0..100)
215 *
216 * Returns:
217 * <gdImagePtr> on success or NULL
218 *
219 * See also:
220 * <gdCropMode>, <gdImageAutoCrop> or <gdImageCrop>
221 */
gdImageCropThreshold(gdImagePtr im,const unsigned int color,const float threshold)222 gdImagePtr gdImageCropThreshold(gdImagePtr im, const unsigned int color, const float threshold)
223 {
224 const int width = gdImageSX(im);
225 const int height = gdImageSY(im);
226
227 int x,y;
228 int match;
229 gdRect crop;
230
231 crop.x = 0;
232 crop.y = 0;
233 crop.width = 0;
234 crop.height = 0;
235
236 /* Pierre: crop everything sounds bad */
237 if (threshold > 1.0) {
238 return NULL;
239 }
240
241 if (!gdImageTrueColor(im) && color >= gdImageColorsTotal(im)) {
242 return NULL;
243 }
244
245 /* TODO: Add gdImageGetRowPtr and works with ptr at the row level
246 * for the true color and palette images
247 * new formats will simply work with ptr
248 */
249 match = 1;
250 for (y = 0; match && y < height; y++) {
251 for (x = 0; match && x < width; x++) {
252 match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
253 }
254 }
255
256 /* Whole image would be cropped > bye */
257 if (match) {
258 return NULL;
259 }
260
261 crop.y = y - 1;
262
263 match = 1;
264 for (y = height - 1; match && y >= 0; y--) {
265 for (x = 0; match && x < width; x++) {
266 match = (gdColorMatch(im, color, gdImageGetPixel(im, x, y), threshold)) > 0;
267 }
268 }
269 crop.height = y - crop.y + 2;
270
271 match = 1;
272 for (x = 0; match && x < width; x++) {
273 for (y = 0; match && y < crop.y + crop.height; y++) {
274 match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
275 }
276 }
277 crop.x = x - 1;
278
279 match = 1;
280 for (x = width - 1; match && x >= 0; x--) {
281 for (y = 0; match && y < crop.y + crop.height; y++) {
282 match = (gdColorMatch(im, color, gdImageGetPixel(im, x,y), threshold)) > 0;
283 }
284 }
285 crop.width = x - crop.x + 2;
286
287 return gdImageCrop(im, &crop);
288 }
289
290 /* This algorithm comes from pnmcrop (http://netpbm.sourceforge.net/)
291 * Three steps:
292 * - if 3 corners are equal.
293 * - if two are equal.
294 * - Last solution: average the colors
295 */
gdGuessBackgroundColorFromCorners(gdImagePtr im,int * color)296 static int gdGuessBackgroundColorFromCorners(gdImagePtr im, int *color)
297 {
298 const int tl = gdImageGetPixel(im, 0, 0);
299 const int tr = gdImageGetPixel(im, gdImageSX(im) - 1, 0);
300 const int bl = gdImageGetPixel(im, 0, gdImageSY(im) -1);
301 const int br = gdImageGetPixel(im, gdImageSX(im) - 1, gdImageSY(im) -1);
302
303 if (tr == bl && tr == br) {
304 *color = tr;
305 return 3;
306 } else if (tl == bl && tl == br) {
307 *color = tl;
308 return 3;
309 } else if (tl == tr && tl == br) {
310 *color = tl;
311 return 3;
312 } else if (tl == tr && tl == bl) {
313 *color = tl;
314 return 3;
315 } else if (tl == tr || tl == bl || tl == br) {
316 *color = tl;
317 return 2;
318 } else if (tr == bl || tr == br) {
319 *color = tr;
320 return 2;
321 } else if (br == bl) {
322 *color = bl;
323 return 2;
324 } else {
325 register int r,b,g,a;
326
327 r = (int)(0.5f + (gdImageRed(im, tl) + gdImageRed(im, tr) + gdImageRed(im, bl) + gdImageRed(im, br)) / 4);
328 g = (int)(0.5f + (gdImageGreen(im, tl) + gdImageGreen(im, tr) + gdImageGreen(im, bl) + gdImageGreen(im, br)) / 4);
329 b = (int)(0.5f + (gdImageBlue(im, tl) + gdImageBlue(im, tr) + gdImageBlue(im, bl) + gdImageBlue(im, br)) / 4);
330 a = (int)(0.5f + (gdImageAlpha(im, tl) + gdImageAlpha(im, tr) + gdImageAlpha(im, bl) + gdImageAlpha(im, br)) / 4);
331 *color = gdImageColorClosestAlpha(im, r, g, b, a);
332 return 0;
333 }
334 }
335
gdColorMatch(gdImagePtr im,int col1,int col2,float threshold)336 static int gdColorMatch(gdImagePtr im, int col1, int col2, float threshold)
337 {
338 const int dr = gdImageRed(im, col1) - gdImageRed(im, col2);
339 const int dg = gdImageGreen(im, col1) - gdImageGreen(im, col2);
340 const int db = gdImageBlue(im, col1) - gdImageBlue(im, col2);
341 const int da = gdImageAlpha(im, col1) - gdImageAlpha(im, col2);
342 const double dist = sqrt(dr * dr + dg * dg + db * db + da * da);
343 const double dist_perc = sqrt(dist / (255^2 + 255^2 + 255^2));
344 return (dist_perc <= threshold);
345 //return (100.0 * dist / 195075) < threshold;
346 }
347
348 /*
349 * To be implemented when we have more image formats.
350 * Buffer like gray8 gray16 or rgb8 will require some tweak
351 * and can be done in this function (called from the autocrop
352 * function. (Pierre)
353 */
354 #if 0
355 static int colors_equal (const int col1, const in col2)
356 {
357
358 }
359 #endif
360
