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 #ifdef _FX_MANAGED_CODE_ 42 #define my_upsampler my_upsampler_m 43 #endif 44 45 /* Private subobject */ 46 47 typedef struct { 48 struct jpeg_upsampler pub; /* public fields */ 49 50 /* Pointer to routine to do actual upsampling/conversion of one row group */ 51 JMETHOD(void, upmethod, (j_decompress_ptr cinfo, 52 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, 53 JSAMPARRAY output_buf)); 54 55 /* Private state for YCC->RGB conversion */ 56 int * Cr_r_tab; /* => table for Cr to R conversion */ 57 int * Cb_b_tab; /* => table for Cb to B conversion */ 58 INT32 * Cr_g_tab; /* => table for Cr to G conversion */ 59 INT32 * Cb_g_tab; /* => table for Cb to G conversion */ 60 61 /* For 2:1 vertical sampling, we produce two output rows at a time. 62 * We need a "spare" row buffer to hold the second output row if the 63 * application provides just a one-row buffer; we also use the spare 64 * to discard the dummy last row if the image height is odd. 65 */ 66 JSAMPROW spare_row; 67 boolean spare_full; /* T if spare buffer is occupied */ 68 69 JDIMENSION out_row_width; /* samples per output row */ 70 JDIMENSION rows_to_go; /* counts rows remaining in image */ 71 } my_upsampler; 72 73 typedef my_upsampler * my_upsample_ptr; 74 75 #define SCALEBITS 16 /* speediest right-shift on some machines */ 76 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) 77 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) 78 79 80 /* 81 * Initialize tables for YCC->RGB colorspace conversion. 82 * This is taken directly from jdcolor.c; see that file for more info. 83 */ 84 85 LOCAL(void) 86 build_ycc_rgb_table (j_decompress_ptr cinfo) 87 { 88 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 89 int i; 90 INT32 x; 91 SHIFT_TEMPS 92 93 upsample->Cr_r_tab = (int *) 94 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 95 (MAXJSAMPLE+1) * SIZEOF(int)); 96 upsample->Cb_b_tab = (int *) 97 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 98 (MAXJSAMPLE+1) * SIZEOF(int)); 99 upsample->Cr_g_tab = (INT32 *) 100 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 101 (MAXJSAMPLE+1) * SIZEOF(INT32)); 102 upsample->Cb_g_tab = (INT32 *) 103 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 104 (MAXJSAMPLE+1) * SIZEOF(INT32)); 105 106 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { 107 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ 108 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ 109 /* Cr=>R value is nearest int to 1.40200 * x */ 110 upsample->Cr_r_tab[i] = (int) 111 RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS); 112 /* Cb=>B value is nearest int to 1.77200 * x */ 113 upsample->Cb_b_tab[i] = (int) 114 RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS); 115 /* Cr=>G value is scaled-up -0.71414 * x */ 116 upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x; 117 /* Cb=>G value is scaled-up -0.34414 * x */ 118 /* We also add in ONE_HALF so that need not do it in inner loop */ 119 upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF; 120 } 121 } 122 123 124 /* 125 * Initialize for an upsampling pass. 126 */ 127 128 METHODDEF(void) 129 start_pass_merged_upsample (j_decompress_ptr cinfo) 130 { 131 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 132 133 /* Mark the spare buffer empty */ 134 upsample->spare_full = FALSE; 135 /* Initialize total-height counter for detecting bottom of image */ 136 upsample->rows_to_go = cinfo->output_height; 137 } 138 139 140 /* 141 * Control routine to do upsampling (and color conversion). 142 * 143 * The control routine just handles the row buffering considerations. 144 */ 145 146 METHODDEF(void) 147 merged_2v_upsample (j_decompress_ptr cinfo, 148 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, 149 JDIMENSION in_row_groups_avail, 150 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 151 JDIMENSION out_rows_avail) 152 /* 2:1 vertical sampling case: may need a spare row. */ 153 { 154 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 155 JSAMPROW work_ptrs[2]; 156 JDIMENSION num_rows; /* number of rows returned to caller */ 157 158 if (upsample->spare_full) { 159 /* If we have a spare row saved from a previous cycle, just return it. */ 160 jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0, 161 1, upsample->out_row_width); 162 num_rows = 1; 163 upsample->spare_full = FALSE; 164 } else { 165 /* Figure number of rows to return to caller. */ 166 num_rows = 2; 167 /* Not more than the distance to the end of the image. */ 168 if (num_rows > upsample->rows_to_go) 169 num_rows = upsample->rows_to_go; 170 /* And not more than what the client can accept: */ 171 out_rows_avail -= *out_row_ctr; 172 if (num_rows > out_rows_avail) 173 num_rows = out_rows_avail; 174 /* Create output pointer array for upsampler. */ 175 work_ptrs[0] = output_buf[*out_row_ctr]; 176 if (num_rows > 1) { 177 work_ptrs[1] = output_buf[*out_row_ctr + 1]; 178 } else { 179 work_ptrs[1] = upsample->spare_row; 180 upsample->spare_full = TRUE; 181 } 182 /* Now do the upsampling. */ 183 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs); 184 } 185 186 /* Adjust counts */ 187 *out_row_ctr += num_rows; 188 upsample->rows_to_go -= num_rows; 189 /* When the buffer is emptied, declare this input row group consumed */ 190 if (! upsample->spare_full) 191 (*in_row_group_ctr)++; 192 } 193 194 195 METHODDEF(void) 196 merged_1v_upsample (j_decompress_ptr cinfo, 197 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, 198 JDIMENSION in_row_groups_avail, 199 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, 200 JDIMENSION out_rows_avail) 201 /* 1:1 vertical sampling case: much easier, never need a spare row. */ 202 { 203 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 204 205 /* Just do the upsampling. */ 206 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, 207 output_buf + *out_row_ctr); 208 /* Adjust counts */ 209 (*out_row_ctr)++; 210 (*in_row_group_ctr)++; 211 } 212 213 214 /* 215 * These are the routines invoked by the control routines to do 216 * the actual upsampling/conversion. One row group is processed per call. 217 * 218 * Note: since we may be writing directly into application-supplied buffers, 219 * we have to be honest about the output width; we can't assume the buffer 220 * has been rounded up to an even width. 221 */ 222 223 224 /* 225 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical. 226 */ 227 228 METHODDEF(void) 229 h2v1_merged_upsample (j_decompress_ptr cinfo, 230 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, 231 JSAMPARRAY output_buf) 232 { 233 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 234 register int y, cred, cgreen, cblue; 235 int cb, cr; 236 register JSAMPROW outptr; 237 JSAMPROW inptr0, inptr1, inptr2; 238 JDIMENSION col; 239 /* copy these pointers into registers if possible */ 240 register JSAMPLE * range_limit = cinfo->sample_range_limit; 241 int * Crrtab = upsample->Cr_r_tab; 242 int * Cbbtab = upsample->Cb_b_tab; 243 INT32 * Crgtab = upsample->Cr_g_tab; 244 INT32 * Cbgtab = upsample->Cb_g_tab; 245 SHIFT_TEMPS 246 247 inptr0 = input_buf[0][in_row_group_ctr]; 248 inptr1 = input_buf[1][in_row_group_ctr]; 249 inptr2 = input_buf[2][in_row_group_ctr]; 250 outptr = output_buf[0]; 251 /* Loop for each pair of output pixels */ 252 for (col = cinfo->output_width >> 1; col > 0; col--) { 253 /* Do the chroma part of the calculation */ 254 cb = GETJSAMPLE(*inptr1++); 255 cr = GETJSAMPLE(*inptr2++); 256 cred = Crrtab[cr]; 257 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); 258 cblue = Cbbtab[cb]; 259 /* Fetch 2 Y values and emit 2 pixels */ 260 y = GETJSAMPLE(*inptr0++); 261 outptr[RGB_RED] = range_limit[y + cred]; 262 outptr[RGB_GREEN] = range_limit[y + cgreen]; 263 outptr[RGB_BLUE] = range_limit[y + cblue]; 264 outptr += RGB_PIXELSIZE; 265 y = GETJSAMPLE(*inptr0++); 266 outptr[RGB_RED] = range_limit[y + cred]; 267 outptr[RGB_GREEN] = range_limit[y + cgreen]; 268 outptr[RGB_BLUE] = range_limit[y + cblue]; 269 outptr += RGB_PIXELSIZE; 270 } 271 /* If image width is odd, do the last output column separately */ 272 if (cinfo->output_width & 1) { 273 cb = GETJSAMPLE(*inptr1); 274 cr = GETJSAMPLE(*inptr2); 275 cred = Crrtab[cr]; 276 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); 277 cblue = Cbbtab[cb]; 278 y = GETJSAMPLE(*inptr0); 279 outptr[RGB_RED] = range_limit[y + cred]; 280 outptr[RGB_GREEN] = range_limit[y + cgreen]; 281 outptr[RGB_BLUE] = range_limit[y + cblue]; 282 } 283 } 284 285 286 /* 287 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical. 288 */ 289 290 METHODDEF(void) 291 h2v2_merged_upsample (j_decompress_ptr cinfo, 292 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, 293 JSAMPARRAY output_buf) 294 { 295 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; 296 register int y, cred, cgreen, cblue; 297 int cb, cr; 298 register JSAMPROW outptr0, outptr1; 299 JSAMPROW inptr00, inptr01, inptr1, inptr2; 300 JDIMENSION col; 301 /* copy these pointers into registers if possible */ 302 register JSAMPLE * range_limit = cinfo->sample_range_limit; 303 int * Crrtab = upsample->Cr_r_tab; 304 int * Cbbtab = upsample->Cb_b_tab; 305 INT32 * Crgtab = upsample->Cr_g_tab; 306 INT32 * Cbgtab = upsample->Cb_g_tab; 307 SHIFT_TEMPS 308 309 inptr00 = input_buf[0][in_row_group_ctr*2]; 310 inptr01 = input_buf[0][in_row_group_ctr*2 + 1]; 311 inptr1 = input_buf[1][in_row_group_ctr]; 312 inptr2 = input_buf[2][in_row_group_ctr]; 313 outptr0 = output_buf[0]; 314 outptr1 = output_buf[1]; 315 /* Loop for each group of output pixels */ 316 for (col = cinfo->output_width >> 1; col > 0; col--) { 317 /* Do the chroma part of the calculation */ 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 /* Fetch 4 Y values and emit 4 pixels */ 324 y = GETJSAMPLE(*inptr00++); 325 outptr0[RGB_RED] = range_limit[y + cred]; 326 outptr0[RGB_GREEN] = range_limit[y + cgreen]; 327 outptr0[RGB_BLUE] = range_limit[y + cblue]; 328 outptr0 += RGB_PIXELSIZE; 329 y = GETJSAMPLE(*inptr00++); 330 outptr0[RGB_RED] = range_limit[y + cred]; 331 outptr0[RGB_GREEN] = range_limit[y + cgreen]; 332 outptr0[RGB_BLUE] = range_limit[y + cblue]; 333 outptr0 += RGB_PIXELSIZE; 334 y = GETJSAMPLE(*inptr01++); 335 outptr1[RGB_RED] = range_limit[y + cred]; 336 outptr1[RGB_GREEN] = range_limit[y + cgreen]; 337 outptr1[RGB_BLUE] = range_limit[y + cblue]; 338 outptr1 += RGB_PIXELSIZE; 339 y = GETJSAMPLE(*inptr01++); 340 outptr1[RGB_RED] = range_limit[y + cred]; 341 outptr1[RGB_GREEN] = range_limit[y + cgreen]; 342 outptr1[RGB_BLUE] = range_limit[y + cblue]; 343 outptr1 += RGB_PIXELSIZE; 344 } 345 /* If image width is odd, do the last output column separately */ 346 if (cinfo->output_width & 1) { 347 cb = GETJSAMPLE(*inptr1); 348 cr = GETJSAMPLE(*inptr2); 349 cred = Crrtab[cr]; 350 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); 351 cblue = Cbbtab[cb]; 352 y = GETJSAMPLE(*inptr00); 353 outptr0[RGB_RED] = range_limit[y + cred]; 354 outptr0[RGB_GREEN] = range_limit[y + cgreen]; 355 outptr0[RGB_BLUE] = range_limit[y + cblue]; 356 y = GETJSAMPLE(*inptr01); 357 outptr1[RGB_RED] = range_limit[y + cred]; 358 outptr1[RGB_GREEN] = range_limit[y + cgreen]; 359 outptr1[RGB_BLUE] = range_limit[y + cblue]; 360 } 361 } 362 363 364 /* 365 * Module initialization routine for merged upsampling/color conversion. 366 * 367 * NB: this is called under the conditions determined by use_merged_upsample() 368 * in jdmaster.c. That routine MUST correspond to the actual capabilities 369 * of this module; no safety checks are made here. 370 */ 371 372 GLOBAL(void) 373 jinit_merged_upsampler (j_decompress_ptr cinfo) 374 { 375 my_upsample_ptr upsample; 376 377 upsample = (my_upsample_ptr) 378 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 379 SIZEOF(my_upsampler)); 380 cinfo->upsample = (struct jpeg_upsampler *) upsample; 381 upsample->pub.start_pass = start_pass_merged_upsample; 382 upsample->pub.need_context_rows = FALSE; 383 384 upsample->out_row_width = cinfo->output_width * cinfo->out_color_components; 385 386 if (cinfo->max_v_samp_factor == 2) { 387 upsample->pub.upsample = merged_2v_upsample; 388 upsample->upmethod = h2v2_merged_upsample; 389 /* Allocate a spare row buffer */ 390 upsample->spare_row = (JSAMPROW) 391 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 392 (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE))); 393 } else { 394 upsample->pub.upsample = merged_1v_upsample; 395 upsample->upmethod = h2v1_merged_upsample; 396 /* No spare row needed */ 397 upsample->spare_row = NULL; 398 } 399 400 build_ycc_rgb_table(cinfo); 401 } 402 403 #endif /* UPSAMPLE_MERGING_SUPPORTED */ 404
