| 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 | JPEG_INT32 * Cr_g_tab; /* => table for Cr to G conversion */ |
| 56 | JPEG_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 | wxjpeg_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 ((JPEG_INT32) 1 << (SCALEBITS-1)) |
| 74 | #define FIX(x) ((JPEG_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 | JPEG_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 = (JPEG_INT32 *) |
| 97 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 98 | (MAXJSAMPLE+1) * SIZEOF(JPEG_INT32)); |
| 99 | upsample->Cb_g_tab = (JPEG_INT32 *) |
| 100 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 101 | (MAXJSAMPLE+1) * SIZEOF(JPEG_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 | JPEG_INT32 * Crgtab = upsample->Cr_g_tab; |
| 241 | JPEG_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 | |
| 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 | JPEG_INT32 * Crgtab = upsample->Cr_g_tab; |
| 302 | JPEG_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 */ |