Details | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
6417 | ashmew2 | 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< |
||
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 | }>>>>>>=> |