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e1929140 RR |
1 | /* |
2 | * jdmerge.c | |
3 | * | |
4 | * Copyright (C) 1994-1996, 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 code for merged upsampling/color conversion. | |
9 | * | |
10 | * This file combines functions from jdsample.c and jdcolor.c; | |
11 | * read those files first to understand what's going on. | |
12 | * | |
13 | * When the chroma components are to be upsampled by simple replication | |
14 | * (ie, box filtering), we can save some work in color conversion by | |
15 | * calculating all the output pixels corresponding to a pair of chroma | |
16 | * samples at one time. In the conversion equations | |
17 | * R = Y + K1 * Cr | |
18 | * G = Y + K2 * Cb + K3 * Cr | |
19 | * B = Y + K4 * Cb | |
20 | * only the Y term varies among the group of pixels corresponding to a pair | |
21 | * of chroma samples, so the rest of the terms can be calculated just once. | |
22 | * At typical sampling ratios, this eliminates half or three-quarters of the | |
23 | * multiplications needed for color conversion. | |
24 | * | |
25 | * This file currently provides implementations for the following cases: | |
26 | * YCbCr => RGB color conversion only. | |
27 | * Sampling ratios of 2h1v or 2h2v. | |
28 | * No scaling needed at upsample time. | |
29 | * Corner-aligned (non-CCIR601) sampling alignment. | |
30 | * Other special cases could be added, but in most applications these are | |
31 | * the only common cases. (For uncommon cases we fall back on the more | |
32 | * general code in jdsample.c and jdcolor.c.) | |
33 | */ | |
34 | ||
35 | #define JPEG_INTERNALS | |
36 | #include "jinclude.h" | |
37 | #include "jpeglib.h" | |
38 | ||
39 | #ifdef UPSAMPLE_MERGING_SUPPORTED | |
40 | ||
41 | ||
42 | /* Private subobject */ | |
43 | ||
44 | typedef struct { | |
45 | struct jpeg_upsampler pub; /* public fields */ | |
46 | ||
47 | /* Pointer to routine to do actual upsampling/conversion of one row group */ | |
48 | JMETHOD(void, upmethod, (j_decompress_ptr cinfo, | |
49 | JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, | |
50 | JSAMPARRAY output_buf)); | |
51 | ||
52 | /* Private state for YCC->RGB conversion */ | |
53 | int * Cr_r_tab; /* => table for Cr to R conversion */ | |
54 | int * Cb_b_tab; /* => table for Cb to B conversion */ | |
55 | INT32 * Cr_g_tab; /* => table for Cr to G conversion */ | |
56 | INT32 * Cb_g_tab; /* => table for Cb to G conversion */ | |
57 | ||
58 | /* For 2:1 vertical sampling, we produce two output rows at a time. | |
59 | * We need a "spare" row buffer to hold the second output row if the | |
60 | * application provides just a one-row buffer; we also use the spare | |
61 | * to discard the dummy last row if the image height is odd. | |
62 | */ | |
63 | JSAMPROW spare_row; | |
64 | boolean spare_full; /* T if spare buffer is occupied */ | |
65 | ||
66 | JDIMENSION out_row_width; /* samples per output row */ | |
67 | JDIMENSION rows_to_go; /* counts rows remaining in image */ | |
68 | } my_upsampler; | |
69 | ||
70 | typedef my_upsampler * my_upsample_ptr; | |
71 | ||
72 | #define SCALEBITS 16 /* speediest right-shift on some machines */ | |
73 | #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) | |
74 | #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) | |
75 | ||
76 | ||
77 | /* | |
78 | * Initialize tables for YCC->RGB colorspace conversion. | |
79 | * This is taken directly from jdcolor.c; see that file for more info. | |
80 | */ | |
81 | ||
82 | LOCAL(void) | |
83 | build_ycc_rgb_table (j_decompress_ptr cinfo) | |
84 | { | |
85 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
86 | int i; | |
87 | INT32 x; | |
88 | SHIFT_TEMPS | |
89 | ||
90 | upsample->Cr_r_tab = (int *) | |
91 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
92 | (MAXJSAMPLE+1) * SIZEOF(int)); | |
93 | upsample->Cb_b_tab = (int *) | |
94 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
95 | (MAXJSAMPLE+1) * SIZEOF(int)); | |
96 | upsample->Cr_g_tab = (INT32 *) | |
97 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
98 | (MAXJSAMPLE+1) * SIZEOF(INT32)); | |
99 | upsample->Cb_g_tab = (INT32 *) | |
100 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
101 | (MAXJSAMPLE+1) * SIZEOF(INT32)); | |
102 | ||
103 | for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { | |
104 | /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ | |
105 | /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ | |
106 | /* Cr=>R value is nearest int to 1.40200 * x */ | |
107 | upsample->Cr_r_tab[i] = (int) | |
108 | RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS); | |
109 | /* Cb=>B value is nearest int to 1.77200 * x */ | |
110 | upsample->Cb_b_tab[i] = (int) | |
111 | RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS); | |
112 | /* Cr=>G value is scaled-up -0.71414 * x */ | |
113 | upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x; | |
114 | /* Cb=>G value is scaled-up -0.34414 * x */ | |
115 | /* We also add in ONE_HALF so that need not do it in inner loop */ | |
116 | upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF; | |
117 | } | |
118 | } | |
119 | ||
120 | ||
121 | /* | |
122 | * Initialize for an upsampling pass. | |
123 | */ | |
124 | ||
125 | METHODDEF(void) | |
126 | start_pass_merged_upsample (j_decompress_ptr cinfo) | |
127 | { | |
128 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
129 | ||
130 | /* Mark the spare buffer empty */ | |
131 | upsample->spare_full = FALSE; | |
132 | /* Initialize total-height counter for detecting bottom of image */ | |
133 | upsample->rows_to_go = cinfo->output_height; | |
134 | } | |
135 | ||
136 | ||
137 | /* | |
138 | * Control routine to do upsampling (and color conversion). | |
139 | * | |
140 | * The control routine just handles the row buffering considerations. | |
141 | */ | |
142 | ||
143 | METHODDEF(void) | |
144 | merged_2v_upsample (j_decompress_ptr cinfo, | |
145 | JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, | |
146 | JDIMENSION in_row_groups_avail, | |
147 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, | |
148 | JDIMENSION out_rows_avail) | |
149 | /* 2:1 vertical sampling case: may need a spare row. */ | |
150 | { | |
151 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
152 | JSAMPROW work_ptrs[2]; | |
153 | JDIMENSION num_rows; /* number of rows returned to caller */ | |
154 | ||
155 | if (upsample->spare_full) { | |
156 | /* If we have a spare row saved from a previous cycle, just return it. */ | |
157 | jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0, | |
158 | 1, upsample->out_row_width); | |
159 | num_rows = 1; | |
160 | upsample->spare_full = FALSE; | |
161 | } else { | |
162 | /* Figure number of rows to return to caller. */ | |
163 | num_rows = 2; | |
164 | /* Not more than the distance to the end of the image. */ | |
165 | if (num_rows > upsample->rows_to_go) | |
166 | num_rows = upsample->rows_to_go; | |
167 | /* And not more than what the client can accept: */ | |
168 | out_rows_avail -= *out_row_ctr; | |
169 | if (num_rows > out_rows_avail) | |
170 | num_rows = out_rows_avail; | |
171 | /* Create output pointer array for upsampler. */ | |
172 | work_ptrs[0] = output_buf[*out_row_ctr]; | |
173 | if (num_rows > 1) { | |
174 | work_ptrs[1] = output_buf[*out_row_ctr + 1]; | |
175 | } else { | |
176 | work_ptrs[1] = upsample->spare_row; | |
177 | upsample->spare_full = TRUE; | |
178 | } | |
179 | /* Now do the upsampling. */ | |
180 | (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs); | |
181 | } | |
182 | ||
183 | /* Adjust counts */ | |
184 | *out_row_ctr += num_rows; | |
185 | upsample->rows_to_go -= num_rows; | |
186 | /* When the buffer is emptied, declare this input row group consumed */ | |
187 | if (! upsample->spare_full) | |
188 | (*in_row_group_ctr)++; | |
189 | } | |
190 | ||
191 | ||
192 | METHODDEF(void) | |
193 | merged_1v_upsample (j_decompress_ptr cinfo, | |
194 | JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, | |
195 | JDIMENSION in_row_groups_avail, | |
196 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, | |
197 | JDIMENSION out_rows_avail) | |
198 | /* 1:1 vertical sampling case: much easier, never need a spare row. */ | |
199 | { | |
200 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
201 | ||
202 | /* Just do the upsampling. */ | |
203 | (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, | |
204 | output_buf + *out_row_ctr); | |
205 | /* Adjust counts */ | |
206 | (*out_row_ctr)++; | |
207 | (*in_row_group_ctr)++; | |
208 | } | |
209 | ||
210 | ||
211 | /* | |
212 | * These are the routines invoked by the control routines to do | |
213 | * the actual upsampling/conversion. One row group is processed per call. | |
214 | * | |
215 | * Note: since we may be writing directly into application-supplied buffers, | |
216 | * we have to be honest about the output width; we can't assume the buffer | |
217 | * has been rounded up to an even width. | |
218 | */ | |
219 | ||
220 | ||
221 | /* | |
222 | * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical. | |
223 | */ | |
224 | ||
225 | METHODDEF(void) | |
226 | h2v1_merged_upsample (j_decompress_ptr cinfo, | |
227 | JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, | |
228 | JSAMPARRAY output_buf) | |
229 | { | |
230 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
231 | register int y, cred, cgreen, cblue; | |
232 | int cb, cr; | |
233 | register JSAMPROW outptr; | |
234 | JSAMPROW inptr0, inptr1, inptr2; | |
235 | JDIMENSION col; | |
236 | /* copy these pointers into registers if possible */ | |
237 | register JSAMPLE * range_limit = cinfo->sample_range_limit; | |
238 | int * Crrtab = upsample->Cr_r_tab; | |
239 | int * Cbbtab = upsample->Cb_b_tab; | |
240 | INT32 * Crgtab = upsample->Cr_g_tab; | |
241 | INT32 * Cbgtab = upsample->Cb_g_tab; | |
242 | SHIFT_TEMPS | |
243 | ||
244 | inptr0 = input_buf[0][in_row_group_ctr]; | |
245 | inptr1 = input_buf[1][in_row_group_ctr]; | |
246 | inptr2 = input_buf[2][in_row_group_ctr]; | |
247 | outptr = output_buf[0]; | |
248 | /* Loop for each pair of output pixels */ | |
249 | for (col = cinfo->output_width >> 1; col > 0; col--) { | |
250 | /* Do the chroma part of the calculation */ | |
251 | cb = GETJSAMPLE(*inptr1++); | |
252 | cr = GETJSAMPLE(*inptr2++); | |
253 | cred = Crrtab[cr]; | |
254 | cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); | |
255 | cblue = Cbbtab[cb]; | |
256 | /* Fetch 2 Y values and emit 2 pixels */ | |
257 | y = GETJSAMPLE(*inptr0++); | |
258 | outptr[RGB_RED] = range_limit[y + cred]; | |
259 | outptr[RGB_GREEN] = range_limit[y + cgreen]; | |
260 | outptr[RGB_BLUE] = range_limit[y + cblue]; | |
261 | outptr += RGB_PIXELSIZE; | |
262 | y = GETJSAMPLE(*inptr0++); | |
263 | outptr[RGB_RED] = range_limit[y + cred]; | |
264 | outptr[RGB_GREEN] = range_limit[y + cgreen]; | |
265 | outptr[RGB_BLUE] = range_limit[y + cblue]; | |
266 | outptr += RGB_PIXELSIZE; | |
267 | } | |
268 | /* If image width is odd, do the last output column separately */ | |
269 | if (cinfo->output_width & 1) { | |
270 | cb = GETJSAMPLE(*inptr1); | |
271 | cr = GETJSAMPLE(*inptr2); | |
272 | cred = Crrtab[cr]; | |
273 | cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); | |
274 | cblue = Cbbtab[cb]; | |
275 | y = GETJSAMPLE(*inptr0); | |
276 | outptr[RGB_RED] = range_limit[y + cred]; | |
277 | outptr[RGB_GREEN] = range_limit[y + cgreen]; | |
278 | outptr[RGB_BLUE] = range_limit[y + cblue]; | |
279 | } | |
280 | } | |
281 | ||
e1929140 RR |
282 | /* |
283 | * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical. | |
284 | */ | |
285 | ||
286 | METHODDEF(void) | |
287 | h2v2_merged_upsample (j_decompress_ptr cinfo, | |
288 | JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, | |
289 | JSAMPARRAY output_buf) | |
290 | { | |
291 | my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; | |
292 | register int y, cred, cgreen, cblue; | |
293 | int cb, cr; | |
294 | register JSAMPROW outptr0, outptr1; | |
295 | JSAMPROW inptr00, inptr01, inptr1, inptr2; | |
296 | JDIMENSION col; | |
297 | /* copy these pointers into registers if possible */ | |
298 | register JSAMPLE * range_limit = cinfo->sample_range_limit; | |
299 | int * Crrtab = upsample->Cr_r_tab; | |
300 | int * Cbbtab = upsample->Cb_b_tab; | |
301 | INT32 * Crgtab = upsample->Cr_g_tab; | |
302 | INT32 * Cbgtab = upsample->Cb_g_tab; | |
303 | SHIFT_TEMPS | |
304 | ||
305 | inptr00 = input_buf[0][in_row_group_ctr*2]; | |
306 | inptr01 = input_buf[0][in_row_group_ctr*2 + 1]; | |
307 | inptr1 = input_buf[1][in_row_group_ctr]; | |
308 | inptr2 = input_buf[2][in_row_group_ctr]; | |
309 | outptr0 = output_buf[0]; | |
310 | outptr1 = output_buf[1]; | |
311 | /* Loop for each group of output pixels */ | |
312 | for (col = cinfo->output_width >> 1; col > 0; col--) { | |
313 | /* Do the chroma part of the calculation */ | |
314 | cb = GETJSAMPLE(*inptr1++); | |
315 | cr = GETJSAMPLE(*inptr2++); | |
316 | cred = Crrtab[cr]; | |
317 | cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); | |
318 | cblue = Cbbtab[cb]; | |
319 | /* Fetch 4 Y values and emit 4 pixels */ | |
320 | y = GETJSAMPLE(*inptr00++); | |
321 | outptr0[RGB_RED] = range_limit[y + cred]; | |
322 | outptr0[RGB_GREEN] = range_limit[y + cgreen]; | |
323 | outptr0[RGB_BLUE] = range_limit[y + cblue]; | |
324 | outptr0 += RGB_PIXELSIZE; | |
325 | y = GETJSAMPLE(*inptr00++); | |
326 | outptr0[RGB_RED] = range_limit[y + cred]; | |
327 | outptr0[RGB_GREEN] = range_limit[y + cgreen]; | |
328 | outptr0[RGB_BLUE] = range_limit[y + cblue]; | |
329 | outptr0 += RGB_PIXELSIZE; | |
330 | y = GETJSAMPLE(*inptr01++); | |
331 | outptr1[RGB_RED] = range_limit[y + cred]; | |
332 | outptr1[RGB_GREEN] = range_limit[y + cgreen]; | |
333 | outptr1[RGB_BLUE] = range_limit[y + cblue]; | |
334 | outptr1 += RGB_PIXELSIZE; | |
335 | y = GETJSAMPLE(*inptr01++); | |
336 | outptr1[RGB_RED] = range_limit[y + cred]; | |
337 | outptr1[RGB_GREEN] = range_limit[y + cgreen]; | |
338 | outptr1[RGB_BLUE] = range_limit[y + cblue]; | |
339 | outptr1 += RGB_PIXELSIZE; | |
340 | } | |
341 | /* If image width is odd, do the last output column separately */ | |
342 | if (cinfo->output_width & 1) { | |
343 | cb = GETJSAMPLE(*inptr1); | |
344 | cr = GETJSAMPLE(*inptr2); | |
345 | cred = Crrtab[cr]; | |
346 | cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); | |
347 | cblue = Cbbtab[cb]; | |
348 | y = GETJSAMPLE(*inptr00); | |
349 | outptr0[RGB_RED] = range_limit[y + cred]; | |
350 | outptr0[RGB_GREEN] = range_limit[y + cgreen]; | |
351 | outptr0[RGB_BLUE] = range_limit[y + cblue]; | |
352 | y = GETJSAMPLE(*inptr01); | |
353 | outptr1[RGB_RED] = range_limit[y + cred]; | |
354 | outptr1[RGB_GREEN] = range_limit[y + cgreen]; | |
355 | outptr1[RGB_BLUE] = range_limit[y + cblue]; | |
356 | } | |
357 | } | |
358 | ||
359 | ||
360 | /* | |
361 | * Module initialization routine for merged upsampling/color conversion. | |
362 | * | |
363 | * NB: this is called under the conditions determined by use_merged_upsample() | |
364 | * in jdmaster.c. That routine MUST correspond to the actual capabilities | |
365 | * of this module; no safety checks are made here. | |
366 | */ | |
367 | ||
368 | GLOBAL(void) | |
369 | jinit_merged_upsampler (j_decompress_ptr cinfo) | |
370 | { | |
371 | my_upsample_ptr upsample; | |
372 | ||
373 | upsample = (my_upsample_ptr) | |
374 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
375 | SIZEOF(my_upsampler)); | |
376 | cinfo->upsample = (struct jpeg_upsampler *) upsample; | |
377 | upsample->pub.start_pass = start_pass_merged_upsample; | |
378 | upsample->pub.need_context_rows = FALSE; | |
379 | ||
380 | upsample->out_row_width = cinfo->output_width * cinfo->out_color_components; | |
381 | ||
382 | if (cinfo->max_v_samp_factor == 2) { | |
383 | upsample->pub.upsample = merged_2v_upsample; | |
384 | upsample->upmethod = h2v2_merged_upsample; | |
385 | /* Allocate a spare row buffer */ | |
386 | upsample->spare_row = (JSAMPROW) | |
387 | (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
388 | (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE))); | |
389 | } else { | |
390 | upsample->pub.upsample = merged_1v_upsample; | |
391 | upsample->upmethod = h2v1_merged_upsample; | |
392 | /* No spare row needed */ | |
393 | upsample->spare_row = NULL; | |
394 | } | |
395 | ||
396 | build_ycc_rgb_table(cinfo); | |
397 | } | |
398 | ||
399 | #endif /* UPSAMPLE_MERGING_SUPPORTED */ |