4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
6 * Copyright (C) 2009, 2011, D. R. Commander.
7 * This file is part of the Independent JPEG Group's software.
8 * For conditions of distribution and use, see the accompanying README file.
10 * This file contains code for merged upsampling/color conversion.
12 * This file combines functions from jdsample.c and jdcolor.c;
13 * read those files first to understand what's going on.
15 * When the chroma components are to be upsampled by simple replication
16 * (ie, box filtering), we can save some work in color conversion by
17 * calculating all the output pixels corresponding to a pair of chroma
18 * samples at one time. In the conversion equations
20 * G = Y + K2 * Cb + K3 * Cr
22 * only the Y term varies among the group of pixels corresponding to a pair
23 * of chroma samples, so the rest of the terms can be calculated just once.
24 * At typical sampling ratios, this eliminates half or three-quarters of the
25 * multiplications needed for color conversion.
27 * This file currently provides implementations for the following cases:
28 * YCbCr => RGB color conversion only.
29 * Sampling ratios of 2h1v or 2h2v.
30 * No scaling needed at upsample time.
31 * Corner-aligned (non-CCIR601) sampling alignment.
32 * Other special cases could be added, but in most applications these are
33 * the only common cases. (For uncommon cases we fall back on the more
34 * general code in jdsample.c and jdcolor.c.)
37 #define JPEG_INTERNALS
43 #ifdef UPSAMPLE_MERGING_SUPPORTED
46 /* Private subobject */
49 struct jpeg_upsampler pub; /* public fields */
51 /* Pointer to routine to do actual upsampling/conversion of one row group */
52 JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
53 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
54 JSAMPARRAY output_buf));
56 /* Private state for YCC->RGB conversion */
57 int * Cr_r_tab; /* => table for Cr to R conversion */
58 int * Cb_b_tab; /* => table for Cb to B conversion */
59 INT32 * Cr_g_tab; /* => table for Cr to G conversion */
60 INT32 * Cb_g_tab; /* => table for Cb to G conversion */
62 /* For 2:1 vertical sampling, we produce two output rows at a time.
63 * We need a "spare" row buffer to hold the second output row if the
64 * application provides just a one-row buffer; we also use the spare
65 * to discard the dummy last row if the image height is odd.
68 boolean spare_full; /* T if spare buffer is occupied */
70 JDIMENSION out_row_width; /* samples per output row */
71 JDIMENSION rows_to_go; /* counts rows remaining in image */
74 typedef my_upsampler * my_upsample_ptr;
76 #define SCALEBITS 16 /* speediest right-shift on some machines */
77 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
78 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
81 /* Include inline routines for colorspace extensions */
89 #define RGB_RED EXT_RGB_RED
90 #define RGB_GREEN EXT_RGB_GREEN
91 #define RGB_BLUE EXT_RGB_BLUE
92 #define RGB_PIXELSIZE EXT_RGB_PIXELSIZE
93 #define h2v1_merged_upsample_internal extrgb_h2v1_merged_upsample_internal
94 #define h2v2_merged_upsample_internal extrgb_h2v2_merged_upsample_internal
100 #undef h2v1_merged_upsample_internal
101 #undef h2v2_merged_upsample_internal
103 #define RGB_RED EXT_RGBX_RED
104 #define RGB_GREEN EXT_RGBX_GREEN
105 #define RGB_BLUE EXT_RGBX_BLUE
106 #define RGB_PIXELSIZE EXT_RGBX_PIXELSIZE
107 #define h2v1_merged_upsample_internal extrgbx_h2v1_merged_upsample_internal
108 #define h2v2_merged_upsample_internal extrgbx_h2v2_merged_upsample_internal
109 #include "jdmrgext.c"
114 #undef h2v1_merged_upsample_internal
115 #undef h2v2_merged_upsample_internal
117 #define RGB_RED EXT_BGR_RED
118 #define RGB_GREEN EXT_BGR_GREEN
119 #define RGB_BLUE EXT_BGR_BLUE
120 #define RGB_PIXELSIZE EXT_BGR_PIXELSIZE
121 #define h2v1_merged_upsample_internal extbgr_h2v1_merged_upsample_internal
122 #define h2v2_merged_upsample_internal extbgr_h2v2_merged_upsample_internal
123 #include "jdmrgext.c"
128 #undef h2v1_merged_upsample_internal
129 #undef h2v2_merged_upsample_internal
131 #define RGB_RED EXT_BGRX_RED
132 #define RGB_GREEN EXT_BGRX_GREEN
133 #define RGB_BLUE EXT_BGRX_BLUE
134 #define RGB_PIXELSIZE EXT_BGRX_PIXELSIZE
135 #define h2v1_merged_upsample_internal extbgrx_h2v1_merged_upsample_internal
136 #define h2v2_merged_upsample_internal extbgrx_h2v2_merged_upsample_internal
137 #include "jdmrgext.c"
142 #undef h2v1_merged_upsample_internal
143 #undef h2v2_merged_upsample_internal
145 #define RGB_RED EXT_XBGR_RED
146 #define RGB_GREEN EXT_XBGR_GREEN
147 #define RGB_BLUE EXT_XBGR_BLUE
148 #define RGB_PIXELSIZE EXT_XBGR_PIXELSIZE
149 #define h2v1_merged_upsample_internal extxbgr_h2v1_merged_upsample_internal
150 #define h2v2_merged_upsample_internal extxbgr_h2v2_merged_upsample_internal
151 #include "jdmrgext.c"
156 #undef h2v1_merged_upsample_internal
157 #undef h2v2_merged_upsample_internal
159 #define RGB_RED EXT_XRGB_RED
160 #define RGB_GREEN EXT_XRGB_GREEN
161 #define RGB_BLUE EXT_XRGB_BLUE
162 #define RGB_PIXELSIZE EXT_XRGB_PIXELSIZE
163 #define h2v1_merged_upsample_internal extxrgb_h2v1_merged_upsample_internal
164 #define h2v2_merged_upsample_internal extxrgb_h2v2_merged_upsample_internal
165 #include "jdmrgext.c"
170 #undef h2v1_merged_upsample_internal
171 #undef h2v2_merged_upsample_internal
175 * Initialize tables for YCC->RGB colorspace conversion.
176 * This is taken directly from jdcolor.c; see that file for more info.
180 build_ycc_rgb_table (j_decompress_ptr cinfo)
182 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
187 upsample->Cr_r_tab = (int *)
188 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
189 (MAXJSAMPLE+1) * SIZEOF(int));
190 upsample->Cb_b_tab = (int *)
191 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
192 (MAXJSAMPLE+1) * SIZEOF(int));
193 upsample->Cr_g_tab = (INT32 *)
194 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
195 (MAXJSAMPLE+1) * SIZEOF(INT32));
196 upsample->Cb_g_tab = (INT32 *)
197 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
198 (MAXJSAMPLE+1) * SIZEOF(INT32));
200 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
201 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
202 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
203 /* Cr=>R value is nearest int to 1.40200 * x */
204 upsample->Cr_r_tab[i] = (int)
205 RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
206 /* Cb=>B value is nearest int to 1.77200 * x */
207 upsample->Cb_b_tab[i] = (int)
208 RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
209 /* Cr=>G value is scaled-up -0.71414 * x */
210 upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;
211 /* Cb=>G value is scaled-up -0.34414 * x */
212 /* We also add in ONE_HALF so that need not do it in inner loop */
213 upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
219 * Initialize for an upsampling pass.
223 start_pass_merged_upsample (j_decompress_ptr cinfo)
225 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
227 /* Mark the spare buffer empty */
228 upsample->spare_full = FALSE;
229 /* Initialize total-height counter for detecting bottom of image */
230 upsample->rows_to_go = cinfo->output_height;
235 * Control routine to do upsampling (and color conversion).
237 * The control routine just handles the row buffering considerations.
241 merged_2v_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 /* 2:1 vertical sampling case: may need a spare row. */
248 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
249 JSAMPROW work_ptrs[2];
250 JDIMENSION num_rows; /* number of rows returned to caller */
253 if (upsample->spare_full) {
254 /* If we have a spare row saved from a previous cycle, just return it. */
255 jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
256 1, upsample->out_row_width);
258 upsample->spare_full = FALSE;
260 int _region_y = (int)cinfo->region_y;
261 _region_y = (_region_y>>1)<<1;
262 if ((cinfo->region_w > 0) && (cinfo->region_h > 0)) {
263 if (((int)cinfo->output_scanline < _region_y) ||
264 ((int)cinfo->output_scanline >= (_region_y + (int)cinfo->region_h)))
267 /* Figure number of rows to return to caller. */
269 /* Not more than the distance to the end of the image. */
270 if (num_rows > upsample->rows_to_go)
271 num_rows = upsample->rows_to_go;
272 /* And not more than what the client can accept: */
273 out_rows_avail -= *out_row_ctr;
274 if (num_rows > out_rows_avail)
275 num_rows = out_rows_avail;
276 /* Create output pointer array for upsampler. */
277 work_ptrs[0] = output_buf[*out_row_ctr];
279 work_ptrs[1] = output_buf[*out_row_ctr + 1];
281 work_ptrs[1] = upsample->spare_row;
282 upsample->spare_full = TRUE;
284 /* Now do the upsampling. */
286 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
290 *out_row_ctr += num_rows;
291 upsample->rows_to_go -= num_rows;
292 /* When the buffer is emptied, declare this input row group consumed */
293 if (! upsample->spare_full)
294 (*in_row_group_ctr)++;
299 merged_1v_upsample (j_decompress_ptr cinfo,
300 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
301 JDIMENSION in_row_groups_avail,
302 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
303 JDIMENSION out_rows_avail)
304 /* 1:1 vertical sampling case: much easier, never need a spare row. */
306 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
308 /* Just do the upsampling. */
309 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
310 output_buf + *out_row_ctr);
313 (*in_row_group_ctr)++;
318 * These are the routines invoked by the control routines to do
319 * the actual upsampling/conversion. One row group is processed per call.
321 * Note: since we may be writing directly into application-supplied buffers,
322 * we have to be honest about the output width; we can't assume the buffer
323 * has been rounded up to an even width.
328 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
332 h2v1_merged_upsample (j_decompress_ptr cinfo,
333 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
334 JSAMPARRAY output_buf)
336 switch (cinfo->out_color_space) {
338 extrgb_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
343 extrgbx_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
347 extbgr_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
352 extbgrx_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
357 extxbgr_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
362 extxrgb_h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
366 h2v1_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
374 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
378 h2v2_merged_upsample (j_decompress_ptr cinfo,
379 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
380 JSAMPARRAY output_buf)
382 switch (cinfo->out_color_space) {
384 extrgb_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
389 extrgbx_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
393 extbgr_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
398 extbgrx_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
403 extxbgr_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
408 extxrgb_h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
412 h2v2_merged_upsample_internal(cinfo, input_buf, in_row_group_ctr,
420 * Module initialization routine for merged upsampling/color conversion.
422 * NB: this is called under the conditions determined by use_merged_upsample()
423 * in jdmaster.c. That routine MUST correspond to the actual capabilities
424 * of this module; no safety checks are made here.
428 jinit_merged_upsampler (j_decompress_ptr cinfo)
430 my_upsample_ptr upsample;
432 upsample = (my_upsample_ptr)
433 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
434 SIZEOF(my_upsampler));
435 cinfo->upsample = (struct jpeg_upsampler *) upsample;
436 upsample->pub.start_pass = start_pass_merged_upsample;
437 upsample->pub.need_context_rows = FALSE;
439 upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
441 if (cinfo->max_v_samp_factor == 2) {
442 upsample->pub.upsample = merged_2v_upsample;
443 if (jsimd_can_h2v2_merged_upsample())
444 upsample->upmethod = jsimd_h2v2_merged_upsample;
446 upsample->upmethod = h2v2_merged_upsample;
447 /* Allocate a spare row buffer */
448 upsample->spare_row = (JSAMPROW)
449 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
450 (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
452 upsample->pub.upsample = merged_1v_upsample;
453 if (jsimd_can_h2v1_merged_upsample())
454 upsample->upmethod = jsimd_h2v1_merged_upsample;
456 upsample->upmethod = h2v1_merged_upsample;
457 /* No spare row needed */
458 upsample->spare_row = NULL;
461 build_ycc_rgb_table(cinfo);
464 #endif /* UPSAMPLE_MERGING_SUPPORTED */