1 /*
2 * jdmerge.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Modified 2013-2017 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains code for merged upsampling/color conversion.
10 *
11 * This file combines functions from jdsample.c and jdcolor.c;
12 * read those files first to understand what's going on.
13 *
14 * When the chroma components are to be upsampled by simple replication
15 * (ie, box filtering), we can save some work in color conversion by
16 * calculating all the output pixels corresponding to a pair of chroma
17 * samples at one time. In the conversion equations
18 * R = Y + K1 * Cr
19 * G = Y + K2 * Cb + K3 * Cr
20 * B = Y + K4 * Cb
21 * only the Y term varies among the group of pixels corresponding to a pair
22 * of chroma samples, so the rest of the terms can be calculated just once.
23 * At typical sampling ratios, this eliminates half or three-quarters of the
24 * multiplications needed for color conversion.
25 *
26 * This file currently provides implementations for the following cases:
27 * YCC => RGB color conversion only (YCbCr or BG_YCC).
28 * Sampling ratios of 2h1v or 2h2v.
29 * No scaling needed at upsample time.
30 * Corner-aligned (non-CCIR601) sampling alignment.
31 * Other special cases could be added, but in most applications these are
32 * the only common cases. (For uncommon cases we fall back on the more
33 * general code in jdsample.c and jdcolor.c.)
34 */
35
36 #define JPEG_INTERNALS
37 #include "jinclude.h"
38 #include "jpeglib.h"
39
40 #ifdef UPSAMPLE_MERGING_SUPPORTED
41
42
43 #if RANGE_BITS < 2
44 /* Deliberate syntax err */
45 Sorry, this code requires 2 or more range extension bits.
46 #endif
47
48
49 /* Private subobject */
50
51 typedef struct {
52 struct jpeg_upsampler pub; /* public fields */
53
54 /* Pointer to routine to do actual upsampling/conversion of one row group */
55 JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
56 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
57 JSAMPARRAY output_buf));
58
59 /* Private state for YCC->RGB conversion */
60 int * Cr_r_tab; /* => table for Cr to R conversion */
61 int * Cb_b_tab; /* => table for Cb to B conversion */
62 INT32 * Cr_g_tab; /* => table for Cr to G conversion */
63 INT32 * Cb_g_tab; /* => table for Cb to G conversion */
64
65 /* For 2:1 vertical sampling, we produce two output rows at a time.
66 * We need a "spare" row buffer to hold the second output row if the
67 * application provides just a one-row buffer; we also use the spare
68 * to discard the dummy last row if the image height is odd.
69 */
70 JSAMPROW spare_row;
71 boolean spare_full; /* T if spare buffer is occupied */
72
73 JDIMENSION out_row_width; /* samples per output row */
74 JDIMENSION rows_to_go; /* counts rows remaining in image */
75 } my_upsampler;
76
77 typedef my_upsampler * my_upsample_ptr;
78
79 #define SCALEBITS 16 /* speediest right-shift on some machines */
80 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
81 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
82
83
84 /*
85 * Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
86 * This is taken directly from jdcolor.c; see that file for more info.
87 */
88
89 LOCAL(void)
build_ycc_rgb_table(j_decompress_ptr cinfo)90 build_ycc_rgb_table (j_decompress_ptr cinfo)
91 /* Normal case, sYCC */
92 {
93 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
94 int i;
95 INT32 x;
96 SHIFT_TEMPS
97
98 upsample->Cr_r_tab = (int *)
99 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
100 (MAXJSAMPLE+1) * SIZEOF(int));
101 upsample->Cb_b_tab = (int *)
102 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
103 (MAXJSAMPLE+1) * SIZEOF(int));
104 upsample->Cr_g_tab = (INT32 *)
105 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
106 (MAXJSAMPLE+1) * SIZEOF(INT32));
107 upsample->Cb_g_tab = (INT32 *)
108 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
109 (MAXJSAMPLE+1) * SIZEOF(INT32));
110
111 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
112 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
113 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
114 /* Cr=>R value is nearest int to 1.402 * x */
115 upsample->Cr_r_tab[i] = (int)
116 RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS);
117 /* Cb=>B value is nearest int to 1.772 * x */
118 upsample->Cb_b_tab[i] = (int)
119 RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, SCALEBITS);
120 /* Cr=>G value is scaled-up -0.714136286 * x */
121 upsample->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
122 /* Cb=>G value is scaled-up -0.344136286 * x */
123 /* We also add in ONE_HALF so that need not do it in inner loop */
124 upsample->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
125 }
126 }
127
128
129 LOCAL(void)
build_bg_ycc_rgb_table(j_decompress_ptr cinfo)130 build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
131 /* Wide gamut case, bg-sYCC */
132 {
133 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
134 int i;
135 INT32 x;
136 SHIFT_TEMPS
137
138 upsample->Cr_r_tab = (int *)
139 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
140 (MAXJSAMPLE+1) * SIZEOF(int));
141 upsample->Cb_b_tab = (int *)
142 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
143 (MAXJSAMPLE+1) * SIZEOF(int));
144 upsample->Cr_g_tab = (INT32 *)
145 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
146 (MAXJSAMPLE+1) * SIZEOF(INT32));
147 upsample->Cb_g_tab = (INT32 *)
148 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
149 (MAXJSAMPLE+1) * SIZEOF(INT32));
150
151 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
152 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
153 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
154 /* Cr=>R value is nearest int to 2.804 * x */
155 upsample->Cr_r_tab[i] = (int)
156 RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS);
157 /* Cb=>B value is nearest int to 3.544 * x */
158 upsample->Cb_b_tab[i] = (int)
159 RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, SCALEBITS);
160 /* Cr=>G value is scaled-up -1.428272572 * x */
161 upsample->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
162 /* Cb=>G value is scaled-up -0.688272572 * x */
163 /* We also add in ONE_HALF so that need not do it in inner loop */
164 upsample->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
165 }
166 }
167
168
169 /*
170 * Initialize for an upsampling pass.
171 */
172
173 METHODDEF(void)
start_pass_merged_upsample(j_decompress_ptr cinfo)174 start_pass_merged_upsample (j_decompress_ptr cinfo)
175 {
176 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
177
178 /* Mark the spare buffer empty */
179 upsample->spare_full = FALSE;
180 /* Initialize total-height counter for detecting bottom of image */
181 upsample->rows_to_go = cinfo->output_height;
182 }
183
184
185 /*
186 * Control routine to do upsampling (and color conversion).
187 *
188 * The control routine just handles the row buffering considerations.
189 */
190
191 METHODDEF(void)
merged_2v_upsample(j_decompress_ptr cinfo,JSAMPIMAGE input_buf,JDIMENSION * in_row_group_ctr,JDIMENSION in_row_groups_avail,JSAMPARRAY output_buf,JDIMENSION * out_row_ctr,JDIMENSION out_rows_avail)192 merged_2v_upsample (j_decompress_ptr cinfo,
193 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
194 JDIMENSION in_row_groups_avail,
195 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
196 JDIMENSION out_rows_avail)
197 /* 2:1 vertical sampling case: may need a spare row. */
198 {
199 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
200 JSAMPROW work_ptrs[2];
201 JDIMENSION num_rows; /* number of rows returned to caller */
202
203 if (upsample->spare_full) {
204 /* If we have a spare row saved from a previous cycle, just return it. */
205 jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
206 1, upsample->out_row_width);
207 num_rows = 1;
208 upsample->spare_full = FALSE;
209 } else {
210 /* Figure number of rows to return to caller. */
211 num_rows = 2;
212 /* Not more than the distance to the end of the image. */
213 if (num_rows > upsample->rows_to_go)
214 num_rows = upsample->rows_to_go;
215 /* And not more than what the client can accept: */
216 out_rows_avail -= *out_row_ctr;
217 if (num_rows > out_rows_avail)
218 num_rows = out_rows_avail;
219 /* Create output pointer array for upsampler. */
220 work_ptrs[0] = output_buf[*out_row_ctr];
221 if (num_rows > 1) {
222 work_ptrs[1] = output_buf[*out_row_ctr + 1];
223 } else {
224 work_ptrs[1] = upsample->spare_row;
225 upsample->spare_full = TRUE;
226 }
227 /* Now do the upsampling. */
228 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
229 }
230
231 /* Adjust counts */
232 *out_row_ctr += num_rows;
233 upsample->rows_to_go -= num_rows;
234 /* When the buffer is emptied, declare this input row group consumed */
235 if (! upsample->spare_full)
236 (*in_row_group_ctr)++;
237 }
238
239
240 METHODDEF(void)
merged_1v_upsample(j_decompress_ptr cinfo,JSAMPIMAGE input_buf,JDIMENSION * in_row_group_ctr,JDIMENSION in_row_groups_avail,JSAMPARRAY output_buf,JDIMENSION * out_row_ctr,JDIMENSION out_rows_avail)241 merged_1v_upsample (j_decompress_ptr cinfo,
242 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
243 JDIMENSION in_row_groups_avail,
244 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
245 JDIMENSION out_rows_avail)
246 /* 1:1 vertical sampling case: much easier, never need a spare row. */
247 {
248 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
249
250 /* Just do the upsampling. */
251 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
252 output_buf + *out_row_ctr);
253 /* Adjust counts */
254 (*out_row_ctr)++;
255 (*in_row_group_ctr)++;
256 }
257
258
259 /*
260 * These are the routines invoked by the control routines to do
261 * the actual upsampling/conversion. One row group is processed per call.
262 *
263 * Note: since we may be writing directly into application-supplied buffers,
264 * we have to be honest about the output width; we can't assume the buffer
265 * has been rounded up to an even width.
266 */
267
268
269 /*
270 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
271 */
272
273 METHODDEF(void)
h2v1_merged_upsample(j_decompress_ptr cinfo,JSAMPIMAGE input_buf,JDIMENSION in_row_group_ctr,JSAMPARRAY output_buf)274 h2v1_merged_upsample (j_decompress_ptr cinfo,
275 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
276 JSAMPARRAY output_buf)
277 {
278 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
279 register int y, cred, cgreen, cblue;
280 int cb, cr;
281 register JSAMPROW outptr;
282 JSAMPROW inptr0, inptr1, inptr2;
283 JDIMENSION col;
284 /* copy these pointers into registers if possible */
285 register JSAMPLE * range_limit = cinfo->sample_range_limit;
286 int * Crrtab = upsample->Cr_r_tab;
287 int * Cbbtab = upsample->Cb_b_tab;
288 INT32 * Crgtab = upsample->Cr_g_tab;
289 INT32 * Cbgtab = upsample->Cb_g_tab;
290 SHIFT_TEMPS
291
292 inptr0 = input_buf[0][in_row_group_ctr];
293 inptr1 = input_buf[1][in_row_group_ctr];
294 inptr2 = input_buf[2][in_row_group_ctr];
295 outptr = output_buf[0];
296 /* Loop for each pair of output pixels */
297 for (col = cinfo->output_width >> 1; col > 0; col--) {
298 /* Do the chroma part of the calculation */
299 cb = GETJSAMPLE(*inptr1++);
300 cr = GETJSAMPLE(*inptr2++);
301 cred = Crrtab[cr];
302 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
303 cblue = Cbbtab[cb];
304 /* Fetch 2 Y values and emit 2 pixels */
305 y = GETJSAMPLE(*inptr0++);
306 outptr[RGB_RED] = range_limit[y + cred];
307 outptr[RGB_GREEN] = range_limit[y + cgreen];
308 outptr[RGB_BLUE] = range_limit[y + cblue];
309 outptr += RGB_PIXELSIZE;
310 y = GETJSAMPLE(*inptr0++);
311 outptr[RGB_RED] = range_limit[y + cred];
312 outptr[RGB_GREEN] = range_limit[y + cgreen];
313 outptr[RGB_BLUE] = range_limit[y + cblue];
314 outptr += RGB_PIXELSIZE;
315 }
316 /* If image width is odd, do the last output column separately */
317 if (cinfo->output_width & 1) {
318 cb = GETJSAMPLE(*inptr1);
319 cr = GETJSAMPLE(*inptr2);
320 cred = Crrtab[cr];
321 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
322 cblue = Cbbtab[cb];
323 y = GETJSAMPLE(*inptr0);
324 outptr[RGB_RED] = range_limit[y + cred];
325 outptr[RGB_GREEN] = range_limit[y + cgreen];
326 outptr[RGB_BLUE] = range_limit[y + cblue];
327 }
328 }
329
330
331 /*
332 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
333 */
334
335 METHODDEF(void)
h2v2_merged_upsample(j_decompress_ptr cinfo,JSAMPIMAGE input_buf,JDIMENSION in_row_group_ctr,JSAMPARRAY output_buf)336 h2v2_merged_upsample (j_decompress_ptr cinfo,
337 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
338 JSAMPARRAY output_buf)
339 {
340 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
341 register int y, cred, cgreen, cblue;
342 int cb, cr;
343 register JSAMPROW outptr0, outptr1;
344 JSAMPROW inptr00, inptr01, inptr1, inptr2;
345 JDIMENSION col;
346 /* copy these pointers into registers if possible */
347 register JSAMPLE * range_limit = cinfo->sample_range_limit;
348 int * Crrtab = upsample->Cr_r_tab;
349 int * Cbbtab = upsample->Cb_b_tab;
350 INT32 * Crgtab = upsample->Cr_g_tab;
351 INT32 * Cbgtab = upsample->Cb_g_tab;
352 SHIFT_TEMPS
353
354 inptr00 = input_buf[0][in_row_group_ctr*2];
355 inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
356 inptr1 = input_buf[1][in_row_group_ctr];
357 inptr2 = input_buf[2][in_row_group_ctr];
358 outptr0 = output_buf[0];
359 outptr1 = output_buf[1];
360 /* Loop for each group of output pixels */
361 for (col = cinfo->output_width >> 1; col > 0; col--) {
362 /* Do the chroma part of the calculation */
363 cb = GETJSAMPLE(*inptr1++);
364 cr = GETJSAMPLE(*inptr2++);
365 cred = Crrtab[cr];
366 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
367 cblue = Cbbtab[cb];
368 /* Fetch 4 Y values and emit 4 pixels */
369 y = GETJSAMPLE(*inptr00++);
370 outptr0[RGB_RED] = range_limit[y + cred];
371 outptr0[RGB_GREEN] = range_limit[y + cgreen];
372 outptr0[RGB_BLUE] = range_limit[y + cblue];
373 outptr0 += RGB_PIXELSIZE;
374 y = GETJSAMPLE(*inptr00++);
375 outptr0[RGB_RED] = range_limit[y + cred];
376 outptr0[RGB_GREEN] = range_limit[y + cgreen];
377 outptr0[RGB_BLUE] = range_limit[y + cblue];
378 outptr0 += RGB_PIXELSIZE;
379 y = GETJSAMPLE(*inptr01++);
380 outptr1[RGB_RED] = range_limit[y + cred];
381 outptr1[RGB_GREEN] = range_limit[y + cgreen];
382 outptr1[RGB_BLUE] = range_limit[y + cblue];
383 outptr1 += RGB_PIXELSIZE;
384 y = GETJSAMPLE(*inptr01++);
385 outptr1[RGB_RED] = range_limit[y + cred];
386 outptr1[RGB_GREEN] = range_limit[y + cgreen];
387 outptr1[RGB_BLUE] = range_limit[y + cblue];
388 outptr1 += RGB_PIXELSIZE;
389 }
390 /* If image width is odd, do the last output column separately */
391 if (cinfo->output_width & 1) {
392 cb = GETJSAMPLE(*inptr1);
393 cr = GETJSAMPLE(*inptr2);
394 cred = Crrtab[cr];
395 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
396 cblue = Cbbtab[cb];
397 y = GETJSAMPLE(*inptr00);
398 outptr0[RGB_RED] = range_limit[y + cred];
399 outptr0[RGB_GREEN] = range_limit[y + cgreen];
400 outptr0[RGB_BLUE] = range_limit[y + cblue];
401 y = GETJSAMPLE(*inptr01);
402 outptr1[RGB_RED] = range_limit[y + cred];
403 outptr1[RGB_GREEN] = range_limit[y + cgreen];
404 outptr1[RGB_BLUE] = range_limit[y + cblue];
405 }
406 }
407
408
409 /*
410 * Module initialization routine for merged upsampling/color conversion.
411 *
412 * NB: this is called under the conditions determined by use_merged_upsample()
413 * in jdmaster.c. That routine MUST correspond to the actual capabilities
414 * of this module; no safety checks are made here.
415 */
416
417 GLOBAL(void)
jinit_merged_upsampler(j_decompress_ptr cinfo)418 jinit_merged_upsampler (j_decompress_ptr cinfo)
419 {
420 my_upsample_ptr upsample;
421
422 upsample = (my_upsample_ptr)
423 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
424 SIZEOF(my_upsampler));
425 cinfo->upsample = &upsample->pub;
426 upsample->pub.start_pass = start_pass_merged_upsample;
427 upsample->pub.need_context_rows = FALSE;
428
429 upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
430
431 if (cinfo->max_v_samp_factor == 2) {
432 upsample->pub.upsample = merged_2v_upsample;
433 upsample->upmethod = h2v2_merged_upsample;
434 /* Allocate a spare row buffer */
435 upsample->spare_row = (JSAMPROW)
436 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
437 (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
438 } else {
439 upsample->pub.upsample = merged_1v_upsample;
440 upsample->upmethod = h2v1_merged_upsample;
441 /* No spare row needed */
442 upsample->spare_row = NULL;
443 }
444
445 if (cinfo->jpeg_color_space == JCS_BG_YCC)
446 build_bg_ycc_rgb_table(cinfo);
447 else
448 build_ycc_rgb_table(cinfo);
449 }
450
451 #endif /* UPSAMPLE_MERGING_SUPPORTED */
452