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) 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) 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) 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) 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) 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) 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) 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) 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