Commit | Line | Data |
---|---|---|
e1929140 RR |
1 | /* |
2 | * jdcolor.c | |
3 | * | |
4 | * Copyright (C) 1991-1997, Thomas G. Lane. | |
5 | * This file is part of the Independent JPEG Group's software. | |
6 | * For conditions of distribution and use, see the accompanying README file. | |
7 | * | |
8 | * This file contains output colorspace conversion routines. | |
9 | */ | |
10 | ||
11 | #define JPEG_INTERNALS | |
12 | #include "jinclude.h" | |
13 | #include "jpeglib.h" | |
14 | ||
15 | ||
16 | /* Private subobject */ | |
17 | ||
18 | typedef struct { | |
19 | struct jpeg_color_deconverter pub; /* public fields */ | |
20 | ||
21 | /* Private state for YCC->RGB conversion */ | |
22 | int * Cr_r_tab; /* => table for Cr to R conversion */ | |
23 | int * Cb_b_tab; /* => table for Cb to B conversion */ | |
24 | INT32 * Cr_g_tab; /* => table for Cr to G conversion */ | |
25 | INT32 * Cb_g_tab; /* => table for Cb to G conversion */ | |
26 | } my_color_deconverter; | |
27 | ||
28 | typedef my_color_deconverter * my_cconvert_ptr; | |
29 | ||
30 | ||
31 | /**************** YCbCr -> RGB conversion: most common case **************/ | |
32 | ||
33 | /* | |
34 | * YCbCr is defined per CCIR 601-1, except that Cb and Cr are | |
35 | * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5. | |
36 | * The conversion equations to be implemented are therefore | |
37 | * R = Y + 1.40200 * Cr | |
38 | * G = Y - 0.34414 * Cb - 0.71414 * Cr | |
39 | * B = Y + 1.77200 * Cb | |
40 | * where Cb and Cr represent the incoming values less CENTERJSAMPLE. | |
41 | * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.) | |
42 | * | |
43 | * To avoid floating-point arithmetic, we represent the fractional constants | |
44 | * as integers scaled up by 2^16 (about 4 digits precision); we have to divide | |
45 | * the products by 2^16, with appropriate rounding, to get the correct answer. | |
46 | * Notice that Y, being an integral input, does not contribute any fraction | |
47 | * so it need not participate in the rounding. | |
48 | * | |
49 | * For even more speed, we avoid doing any multiplications in the inner loop | |
50 | * by precalculating the constants times Cb and Cr for all possible values. | |
51 | * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table); | |
52 | * for 12-bit samples it is still acceptable. It's not very reasonable for | |
53 | * 16-bit samples, but if you want lossless storage you shouldn't be changing | |
54 | * colorspace anyway. | |
55 | * The Cr=>R and Cb=>B values can be rounded to integers in advance; the | |
56 | * values for the G calculation are left scaled up, since we must add them | |
57 | * together before rounding. | |
58 | */ | |
59 | ||
60 | #define SCALEBITS 16 /* speediest right-shift on some machines */ | |
61 | #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) | |
62 | #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) | |
63 | ||
64 | ||
65 | /* | |
66 | * Initialize tables for YCC->RGB colorspace conversion. | |
67 | */ | |
68 | ||
69 | LOCAL(void) | |
70 | build_ycc_rgb_table (j_decompress_ptr cinfo) | |
71 | { | |
72 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
73 | int i; | |
74 | INT32 x; | |
75 | SHIFT_TEMPS | |
76 | ||
77 | cconvert->Cr_r_tab = (int *) | |
78 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
79 | (MAXJSAMPLE+1) * SIZEOF(int)); | |
80 | cconvert->Cb_b_tab = (int *) | |
81 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
82 | (MAXJSAMPLE+1) * SIZEOF(int)); | |
83 | cconvert->Cr_g_tab = (INT32 *) | |
84 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
85 | (MAXJSAMPLE+1) * SIZEOF(INT32)); | |
86 | cconvert->Cb_g_tab = (INT32 *) | |
87 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
88 | (MAXJSAMPLE+1) * SIZEOF(INT32)); | |
89 | ||
90 | for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { | |
91 | /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ | |
92 | /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ | |
93 | /* Cr=>R value is nearest int to 1.40200 * x */ | |
94 | cconvert->Cr_r_tab[i] = (int) | |
95 | RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS); | |
96 | /* Cb=>B value is nearest int to 1.77200 * x */ | |
97 | cconvert->Cb_b_tab[i] = (int) | |
98 | RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS); | |
99 | /* Cr=>G value is scaled-up -0.71414 * x */ | |
100 | cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x; | |
101 | /* Cb=>G value is scaled-up -0.34414 * x */ | |
102 | /* We also add in ONE_HALF so that need not do it in inner loop */ | |
103 | cconvert->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF; | |
104 | } | |
105 | } | |
106 | ||
107 | ||
108 | /* | |
109 | * Convert some rows of samples to the output colorspace. | |
110 | * | |
111 | * Note that we change from noninterleaved, one-plane-per-component format | |
112 | * to interleaved-pixel format. The output buffer is therefore three times | |
113 | * as wide as the input buffer. | |
114 | * A starting row offset is provided only for the input buffer. The caller | |
115 | * can easily adjust the passed output_buf value to accommodate any row | |
116 | * offset required on that side. | |
117 | */ | |
118 | ||
119 | METHODDEF(void) | |
120 | ycc_rgb_convert (j_decompress_ptr cinfo, | |
121 | JSAMPIMAGE input_buf, JDIMENSION input_row, | |
122 | JSAMPARRAY output_buf, int num_rows) | |
123 | { | |
124 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
125 | register int y, cb, cr; | |
126 | register JSAMPROW outptr; | |
127 | register JSAMPROW inptr0, inptr1, inptr2; | |
128 | register JDIMENSION col; | |
129 | JDIMENSION num_cols = cinfo->output_width; | |
130 | /* copy these pointers into registers if possible */ | |
131 | register JSAMPLE * range_limit = cinfo->sample_range_limit; | |
132 | register int * Crrtab = cconvert->Cr_r_tab; | |
133 | register int * Cbbtab = cconvert->Cb_b_tab; | |
134 | register INT32 * Crgtab = cconvert->Cr_g_tab; | |
135 | register INT32 * Cbgtab = cconvert->Cb_g_tab; | |
136 | SHIFT_TEMPS | |
137 | ||
138 | while (--num_rows >= 0) { | |
139 | inptr0 = input_buf[0][input_row]; | |
140 | inptr1 = input_buf[1][input_row]; | |
141 | inptr2 = input_buf[2][input_row]; | |
142 | input_row++; | |
143 | outptr = *output_buf++; | |
144 | for (col = 0; col < num_cols; col++) { | |
145 | y = GETJSAMPLE(inptr0[col]); | |
146 | cb = GETJSAMPLE(inptr1[col]); | |
147 | cr = GETJSAMPLE(inptr2[col]); | |
148 | /* Range-limiting is essential due to noise introduced by DCT losses. */ | |
149 | outptr[RGB_RED] = range_limit[y + Crrtab[cr]]; | |
150 | outptr[RGB_GREEN] = range_limit[y + | |
151 | ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], | |
152 | SCALEBITS))]; | |
153 | outptr[RGB_BLUE] = range_limit[y + Cbbtab[cb]]; | |
154 | outptr += RGB_PIXELSIZE; | |
155 | } | |
156 | } | |
157 | } | |
158 | ||
159 | ||
160 | /**************** Cases other than YCbCr -> RGB **************/ | |
161 | ||
162 | ||
163 | /* | |
164 | * Color conversion for no colorspace change: just copy the data, | |
165 | * converting from separate-planes to interleaved representation. | |
166 | */ | |
167 | ||
168 | METHODDEF(void) | |
169 | null_convert (j_decompress_ptr cinfo, | |
170 | JSAMPIMAGE input_buf, JDIMENSION input_row, | |
171 | JSAMPARRAY output_buf, int num_rows) | |
172 | { | |
173 | register JSAMPROW inptr, outptr; | |
174 | register JDIMENSION count; | |
175 | register int num_components = cinfo->num_components; | |
176 | JDIMENSION num_cols = cinfo->output_width; | |
177 | int ci; | |
178 | ||
179 | while (--num_rows >= 0) { | |
180 | for (ci = 0; ci < num_components; ci++) { | |
181 | inptr = input_buf[ci][input_row]; | |
182 | outptr = output_buf[0] + ci; | |
183 | for (count = num_cols; count > 0; count--) { | |
184 | *outptr = *inptr++; /* needn't bother with GETJSAMPLE() here */ | |
185 | outptr += num_components; | |
186 | } | |
187 | } | |
188 | input_row++; | |
189 | output_buf++; | |
190 | } | |
191 | } | |
192 | ||
193 | ||
194 | /* | |
195 | * Color conversion for grayscale: just copy the data. | |
196 | * This also works for YCbCr -> grayscale conversion, in which | |
197 | * we just copy the Y (luminance) component and ignore chrominance. | |
198 | */ | |
199 | ||
200 | METHODDEF(void) | |
201 | grayscale_convert (j_decompress_ptr cinfo, | |
202 | JSAMPIMAGE input_buf, JDIMENSION input_row, | |
203 | JSAMPARRAY output_buf, int num_rows) | |
204 | { | |
205 | jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0, | |
206 | num_rows, cinfo->output_width); | |
207 | } | |
208 | ||
209 | ||
210 | /* | |
211 | * Convert grayscale to RGB: just duplicate the graylevel three times. | |
212 | * This is provided to support applications that don't want to cope | |
213 | * with grayscale as a separate case. | |
214 | */ | |
215 | ||
216 | METHODDEF(void) | |
217 | gray_rgb_convert (j_decompress_ptr cinfo, | |
218 | JSAMPIMAGE input_buf, JDIMENSION input_row, | |
219 | JSAMPARRAY output_buf, int num_rows) | |
220 | { | |
221 | register JSAMPROW inptr, outptr; | |
222 | register JDIMENSION col; | |
223 | JDIMENSION num_cols = cinfo->output_width; | |
224 | ||
225 | while (--num_rows >= 0) { | |
226 | inptr = input_buf[0][input_row++]; | |
227 | outptr = *output_buf++; | |
228 | for (col = 0; col < num_cols; col++) { | |
229 | /* We can dispense with GETJSAMPLE() here */ | |
230 | outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col]; | |
231 | outptr += RGB_PIXELSIZE; | |
232 | } | |
233 | } | |
234 | } | |
235 | ||
236 | ||
237 | /* | |
238 | * Adobe-style YCCK->CMYK conversion. | |
239 | * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same | |
240 | * conversion as above, while passing K (black) unchanged. | |
241 | * We assume build_ycc_rgb_table has been called. | |
242 | */ | |
243 | ||
244 | METHODDEF(void) | |
245 | ycck_cmyk_convert (j_decompress_ptr cinfo, | |
246 | JSAMPIMAGE input_buf, JDIMENSION input_row, | |
247 | JSAMPARRAY output_buf, int num_rows) | |
248 | { | |
249 | my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
250 | register int y, cb, cr; | |
251 | register JSAMPROW outptr; | |
252 | register JSAMPROW inptr0, inptr1, inptr2, inptr3; | |
253 | register JDIMENSION col; | |
254 | JDIMENSION num_cols = cinfo->output_width; | |
255 | /* copy these pointers into registers if possible */ | |
256 | register JSAMPLE * range_limit = cinfo->sample_range_limit; | |
257 | register int * Crrtab = cconvert->Cr_r_tab; | |
258 | register int * Cbbtab = cconvert->Cb_b_tab; | |
259 | register INT32 * Crgtab = cconvert->Cr_g_tab; | |
260 | register INT32 * Cbgtab = cconvert->Cb_g_tab; | |
261 | SHIFT_TEMPS | |
262 | ||
263 | while (--num_rows >= 0) { | |
264 | inptr0 = input_buf[0][input_row]; | |
265 | inptr1 = input_buf[1][input_row]; | |
266 | inptr2 = input_buf[2][input_row]; | |
267 | inptr3 = input_buf[3][input_row]; | |
268 | input_row++; | |
269 | outptr = *output_buf++; | |
270 | for (col = 0; col < num_cols; col++) { | |
271 | y = GETJSAMPLE(inptr0[col]); | |
272 | cb = GETJSAMPLE(inptr1[col]); | |
273 | cr = GETJSAMPLE(inptr2[col]); | |
274 | /* Range-limiting is essential due to noise introduced by DCT losses. */ | |
275 | outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])]; /* red */ | |
276 | outptr[1] = range_limit[MAXJSAMPLE - (y + /* green */ | |
277 | ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], | |
278 | SCALEBITS)))]; | |
279 | outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])]; /* blue */ | |
280 | /* K passes through unchanged */ | |
281 | outptr[3] = inptr3[col]; /* don't need GETJSAMPLE here */ | |
282 | outptr += 4; | |
283 | } | |
284 | } | |
285 | } | |
286 | ||
287 | ||
288 | /* | |
289 | * Empty method for start_pass. | |
290 | */ | |
291 | ||
292 | METHODDEF(void) | |
293 | start_pass_dcolor (j_decompress_ptr cinfo) | |
294 | { | |
295 | /* no work needed */ | |
296 | } | |
297 | ||
298 | ||
299 | /* | |
300 | * Module initialization routine for output colorspace conversion. | |
301 | */ | |
302 | ||
303 | GLOBAL(void) | |
304 | jinit_color_deconverter (j_decompress_ptr cinfo) | |
305 | { | |
306 | my_cconvert_ptr cconvert; | |
307 | int ci; | |
308 | ||
309 | cconvert = (my_cconvert_ptr) | |
310 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
311 | SIZEOF(my_color_deconverter)); | |
312 | cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert; | |
313 | cconvert->pub.start_pass = start_pass_dcolor; | |
314 | ||
315 | /* Make sure num_components agrees with jpeg_color_space */ | |
316 | switch (cinfo->jpeg_color_space) { | |
317 | case JCS_GRAYSCALE: | |
318 | if (cinfo->num_components != 1) | |
319 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
320 | break; | |
321 | ||
322 | case JCS_RGB: | |
323 | case JCS_YCbCr: | |
324 | if (cinfo->num_components != 3) | |
325 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
326 | break; | |
327 | ||
328 | case JCS_CMYK: | |
329 | case JCS_YCCK: | |
330 | if (cinfo->num_components != 4) | |
331 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
332 | break; | |
333 | ||
334 | default: /* JCS_UNKNOWN can be anything */ | |
335 | if (cinfo->num_components < 1) | |
336 | ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
337 | break; | |
338 | } | |
339 | ||
340 | /* Set out_color_components and conversion method based on requested space. | |
341 | * Also clear the component_needed flags for any unused components, | |
342 | * so that earlier pipeline stages can avoid useless computation. | |
343 | */ | |
344 | ||
345 | switch (cinfo->out_color_space) { | |
346 | case JCS_GRAYSCALE: | |
347 | cinfo->out_color_components = 1; | |
348 | if (cinfo->jpeg_color_space == JCS_GRAYSCALE || | |
349 | cinfo->jpeg_color_space == JCS_YCbCr) { | |
350 | cconvert->pub.color_convert = grayscale_convert; | |
351 | /* For color->grayscale conversion, only the Y (0) component is needed */ | |
352 | for (ci = 1; ci < cinfo->num_components; ci++) | |
353 | cinfo->comp_info[ci].component_needed = FALSE; | |
354 | } else | |
355 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
356 | break; | |
357 | ||
358 | case JCS_RGB: | |
359 | cinfo->out_color_components = RGB_PIXELSIZE; | |
360 | if (cinfo->jpeg_color_space == JCS_YCbCr) { | |
361 | cconvert->pub.color_convert = ycc_rgb_convert; | |
362 | build_ycc_rgb_table(cinfo); | |
363 | } else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) { | |
364 | cconvert->pub.color_convert = gray_rgb_convert; | |
365 | } else if (cinfo->jpeg_color_space == JCS_RGB && RGB_PIXELSIZE == 3) { | |
366 | cconvert->pub.color_convert = null_convert; | |
367 | } else | |
368 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
369 | break; | |
370 | ||
371 | case JCS_CMYK: | |
372 | cinfo->out_color_components = 4; | |
373 | if (cinfo->jpeg_color_space == JCS_YCCK) { | |
374 | cconvert->pub.color_convert = ycck_cmyk_convert; | |
375 | build_ycc_rgb_table(cinfo); | |
376 | } else if (cinfo->jpeg_color_space == JCS_CMYK) { | |
377 | cconvert->pub.color_convert = null_convert; | |
378 | } else | |
379 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
380 | break; | |
381 | ||
382 | default: | |
383 | /* Permit null conversion to same output space */ | |
384 | if (cinfo->out_color_space == cinfo->jpeg_color_space) { | |
385 | cinfo->out_color_components = cinfo->num_components; | |
386 | cconvert->pub.color_convert = null_convert; | |
387 | } else /* unsupported non-null conversion */ | |
388 | ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
389 | break; | |
390 | } | |
391 | ||
392 | if (cinfo->quantize_colors) | |
393 | cinfo->output_components = 1; /* single colormapped output component */ | |
394 | else | |
395 | cinfo->output_components = cinfo->out_color_components; | |
396 | } |