workbench/libs/jpeg/jdmerge.c

   1 /*
   2  * jdmerge.c
   3  *
   4  * Copyright (C) 1994-1996, Thomas G. Lane.
   5  * Modified 2013-2015 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 /* Private subobject */
  44
  45 typedef struct {
  46   struct jpeg_upsampler pub;    /* public fields */
  47
  48   /* Pointer to routine to do actual upsampling/conversion of one row group */
  49   JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
  50                            JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
  51                            JSAMPARRAY output_buf));
  52
  53   /* Private state for YCC->RGB conversion */
  54   int * Cr_r_tab;               /* => table for Cr to R conversion */
  55   int * Cb_b_tab;               /* => table for Cb to B conversion */
  56   INT32 * Cr_g_tab;             /* => table for Cr to G conversion */
  57   INT32 * Cb_g_tab;             /* => table for Cb to G conversion */
  58
  59   /* For 2:1 vertical sampling, we produce two output rows at a time.
  60    * We need a "spare" row buffer to hold the second output row if the
  61    * application provides just a one-row buffer; we also use the spare
  62    * to discard the dummy last row if the image height is odd.
  63    */
  64   JSAMPROW spare_row;
  65   boolean spare_full;           /* T if spare buffer is occupied */
  66
  67   JDIMENSION out_row_width;     /* samples per output row */
  68   JDIMENSION rows_to_go;        /* counts rows remaining in image */
  69 } my_upsampler;
  70
  71 typedef my_upsampler * my_upsample_ptr;
  72
  73 #define SCALEBITS       16      /* speediest right-shift on some machines */
  74 #define ONE_HALF        ((INT32) 1 << (SCALEBITS-1))
  75 #define FIX(x)          ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
  76
  77
  78 /*
  79  * Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion.
  80  * This is taken directly from jdcolor.c; see that file for more info.
  81  */
  82
  83 LOCAL(void)
  84 build_ycc_rgb_table (j_decompress_ptr cinfo)
  85 /* Normal case, sYCC */
  86 {
  87   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
  88   int i;
  89   INT32 x;
  90   SHIFT_TEMPS
  91
  92   upsample->Cr_r_tab = (int *)
  93     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
  94                                 (MAXJSAMPLE+1) * SIZEOF(int));
  95   upsample->Cb_b_tab = (int *)
  96     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
  97                                 (MAXJSAMPLE+1) * SIZEOF(int));
  98   upsample->Cr_g_tab = (INT32 *)
  99     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 100                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 101   upsample->Cb_g_tab = (INT32 *)
 102     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 103                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 104
 105   for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
 106     /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
 107     /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
 108     /* Cr=>R value is nearest int to 1.402 * x */
 109     upsample->Cr_r_tab[i] = (int)
 110                     RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS);
 111     /* Cb=>B value is nearest int to 1.772 * x */
 112     upsample->Cb_b_tab[i] = (int)
 113                     RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, SCALEBITS);
 114     /* Cr=>G value is scaled-up -0.714136286 * x */
 115     upsample->Cr_g_tab[i] = (- FIX(0.714136286)) * x;
 116     /* Cb=>G value is scaled-up -0.344136286 * x */
 117     /* We also add in ONE_HALF so that need not do it in inner loop */
 118     upsample->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF;
 119   }
 120 }
 121
 122
 123 LOCAL(void)
 124 build_bg_ycc_rgb_table (j_decompress_ptr cinfo)
 125 /* Wide gamut case, bg-sYCC */
 126 {
 127   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 128   int i;
 129   INT32 x;
 130   SHIFT_TEMPS
 131
 132   upsample->Cr_r_tab = (int *)
 133     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 134                                 (MAXJSAMPLE+1) * SIZEOF(int));
 135   upsample->Cb_b_tab = (int *)
 136     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 137                                 (MAXJSAMPLE+1) * SIZEOF(int));
 138   upsample->Cr_g_tab = (INT32 *)
 139     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 140                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 141   upsample->Cb_g_tab = (INT32 *)
 142     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 143                                 (MAXJSAMPLE+1) * SIZEOF(INT32));
 144
 145   for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
 146     /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
 147     /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
 148     /* Cr=>R value is nearest int to 2.804 * x */
 149     upsample->Cr_r_tab[i] = (int)
 150                     RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS);
 151     /* Cb=>B value is nearest int to 3.544 * x */
 152     upsample->Cb_b_tab[i] = (int)
 153                     RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, SCALEBITS);
 154     /* Cr=>G value is scaled-up -1.428272572 * x */
 155     upsample->Cr_g_tab[i] = (- FIX(1.428272572)) * x;
 156     /* Cb=>G value is scaled-up -0.688272572 * x */
 157     /* We also add in ONE_HALF so that need not do it in inner loop */
 158     upsample->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF;
 159   }
 160 }
 161
 162
 163 /*
 164  * Initialize for an upsampling pass.
 165  */
 166
 167 METHODDEF(void)
 168 start_pass_merged_upsample (j_decompress_ptr cinfo)
 169 {
 170   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 171
 172   /* Mark the spare buffer empty */
 173   upsample->spare_full = FALSE;
 174   /* Initialize total-height counter for detecting bottom of image */
 175   upsample->rows_to_go = cinfo->output_height;
 176 }
 177
 178
 179 /*
 180  * Control routine to do upsampling (and color conversion).
 181  *
 182  * The control routine just handles the row buffering considerations.
 183  */
 184
 185 METHODDEF(void)
 186 merged_2v_upsample (j_decompress_ptr cinfo,
 187                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 188                     JDIMENSION in_row_groups_avail,
 189                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 190                     JDIMENSION out_rows_avail)
 191 /* 2:1 vertical sampling case: may need a spare row. */
 192 {
 193   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 194   JSAMPROW work_ptrs[2];
 195   JDIMENSION num_rows;          /* number of rows returned to caller */
 196
 197   if (upsample->spare_full) {
 198     /* If we have a spare row saved from a previous cycle, just return it. */
 199     jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
 200                       1, upsample->out_row_width);
 201     num_rows = 1;
 202     upsample->spare_full = FALSE;
 203   } else {
 204     /* Figure number of rows to return to caller. */
 205     num_rows = 2;
 206     /* Not more than the distance to the end of the image. */
 207     if (num_rows > upsample->rows_to_go)
 208       num_rows = upsample->rows_to_go;
 209     /* And not more than what the client can accept: */
 210     out_rows_avail -= *out_row_ctr;
 211     if (num_rows > out_rows_avail)
 212       num_rows = out_rows_avail;
 213     /* Create output pointer array for upsampler. */
 214     work_ptrs[0] = output_buf[*out_row_ctr];
 215     if (num_rows > 1) {
 216       work_ptrs[1] = output_buf[*out_row_ctr + 1];
 217     } else {
 218       work_ptrs[1] = upsample->spare_row;
 219       upsample->spare_full = TRUE;
 220     }
 221     /* Now do the upsampling. */
 222     (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
 223   }
 224
 225   /* Adjust counts */
 226   *out_row_ctr += num_rows;
 227   upsample->rows_to_go -= num_rows;
 228   /* When the buffer is emptied, declare this input row group consumed */
 229   if (! upsample->spare_full)
 230     (*in_row_group_ctr)++;
 231 }
 232
 233
 234 METHODDEF(void)
 235 merged_1v_upsample (j_decompress_ptr cinfo,
 236                     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 237                     JDIMENSION in_row_groups_avail,
 238                     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 239                     JDIMENSION out_rows_avail)
 240 /* 1:1 vertical sampling case: much easier, never need a spare row. */
 241 {
 242   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 243
 244   /* Just do the upsampling. */
 245   (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
 246                          output_buf + *out_row_ctr);
 247   /* Adjust counts */
 248   (*out_row_ctr)++;
 249   (*in_row_group_ctr)++;
 250 }
 251
 252
 253 /*
 254  * These are the routines invoked by the control routines to do
 255  * the actual upsampling/conversion.  One row group is processed per call.
 256  *
 257  * Note: since we may be writing directly into application-supplied buffers,
 258  * we have to be honest about the output width; we can't assume the buffer
 259  * has been rounded up to an even width.
 260  */
 261
 262
 263 /*
 264  * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
 265  */
 266
 267 METHODDEF(void)
 268 h2v1_merged_upsample (j_decompress_ptr cinfo,
 269                       JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
 270                       JSAMPARRAY output_buf)
 271 {
 272   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 273   register int y, cred, cgreen, cblue;
 274   int cb, cr;
 275   register JSAMPROW outptr;
 276   JSAMPROW inptr0, inptr1, inptr2;
 277   JDIMENSION col;
 278   /* copy these pointers into registers if possible */
 279   register JSAMPLE * range_limit = cinfo->sample_range_limit;
 280   int * Crrtab = upsample->Cr_r_tab;
 281   int * Cbbtab = upsample->Cb_b_tab;
 282   INT32 * Crgtab = upsample->Cr_g_tab;
 283   INT32 * Cbgtab = upsample->Cb_g_tab;
 284   SHIFT_TEMPS
 285
 286   inptr0 = input_buf[0][in_row_group_ctr];
 287   inptr1 = input_buf[1][in_row_group_ctr];
 288   inptr2 = input_buf[2][in_row_group_ctr];
 289   outptr = output_buf[0];
 290   /* Loop for each pair of output pixels */
 291   for (col = cinfo->output_width >> 1; col > 0; col--) {
 292     /* Do the chroma part of the calculation */
 293     cb = GETJSAMPLE(*inptr1++);
 294     cr = GETJSAMPLE(*inptr2++);
 295     cred   = Crrtab[cr];
 296     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
 297     cblue  = Cbbtab[cb];
 298     /* Fetch 2 Y values and emit 2 pixels */
 299     y  = GETJSAMPLE(*inptr0++);
 300     outptr[RGB_RED]   = range_limit[y + cred];
 301     outptr[RGB_GREEN] = range_limit[y + cgreen];
 302     outptr[RGB_BLUE]  = range_limit[y + cblue];
 303     outptr += RGB_PIXELSIZE;
 304     y  = GETJSAMPLE(*inptr0++);
 305     outptr[RGB_RED]   = range_limit[y + cred];
 306     outptr[RGB_GREEN] = range_limit[y + cgreen];
 307     outptr[RGB_BLUE]  = range_limit[y + cblue];
 308     outptr += RGB_PIXELSIZE;
 309   }
 310   /* If image width is odd, do the last output column separately */
 311   if (cinfo->output_width & 1) {
 312     cb = GETJSAMPLE(*inptr1);
 313     cr = GETJSAMPLE(*inptr2);
 314     cred   = Crrtab[cr];
 315     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
 316     cblue  = Cbbtab[cb];
 317     y  = GETJSAMPLE(*inptr0);
 318     outptr[RGB_RED]   = range_limit[y + cred];
 319     outptr[RGB_GREEN] = range_limit[y + cgreen];
 320     outptr[RGB_BLUE]  = range_limit[y + cblue];
 321   }
 322 }
 323
 324
 325 /*
 326  * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
 327  */
 328
 329 METHODDEF(void)
 330 h2v2_merged_upsample (j_decompress_ptr cinfo,
 331                       JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
 332                       JSAMPARRAY output_buf)
 333 {
 334   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 335   register int y, cred, cgreen, cblue;
 336   int cb, cr;
 337   register JSAMPROW outptr0, outptr1;
 338   JSAMPROW inptr00, inptr01, inptr1, inptr2;
 339   JDIMENSION col;
 340   /* copy these pointers into registers if possible */
 341   register JSAMPLE * range_limit = cinfo->sample_range_limit;
 342   int * Crrtab = upsample->Cr_r_tab;
 343   int * Cbbtab = upsample->Cb_b_tab;
 344   INT32 * Crgtab = upsample->Cr_g_tab;
 345   INT32 * Cbgtab = upsample->Cb_g_tab;
 346   SHIFT_TEMPS
 347
 348   inptr00 = input_buf[0][in_row_group_ctr*2];
 349   inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
 350   inptr1 = input_buf[1][in_row_group_ctr];
 351   inptr2 = input_buf[2][in_row_group_ctr];
 352   outptr0 = output_buf[0];
 353   outptr1 = output_buf[1];
 354   /* Loop for each group of output pixels */
 355   for (col = cinfo->output_width >> 1; col > 0; col--) {
 356     /* Do the chroma part of the calculation */
 357     cb = GETJSAMPLE(*inptr1++);
 358     cr = GETJSAMPLE(*inptr2++);
 359     cred   = Crrtab[cr];
 360     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
 361     cblue  = Cbbtab[cb];
 362     /* Fetch 4 Y values and emit 4 pixels */
 363     y  = GETJSAMPLE(*inptr00++);
 364     outptr0[RGB_RED]   = range_limit[y + cred];
 365     outptr0[RGB_GREEN] = range_limit[y + cgreen];
 366     outptr0[RGB_BLUE]  = range_limit[y + cblue];
 367     outptr0 += RGB_PIXELSIZE;
 368     y  = GETJSAMPLE(*inptr00++);
 369     outptr0[RGB_RED]   = range_limit[y + cred];
 370     outptr0[RGB_GREEN] = range_limit[y + cgreen];
 371     outptr0[RGB_BLUE]  = range_limit[y + cblue];
 372     outptr0 += RGB_PIXELSIZE;
 373     y  = GETJSAMPLE(*inptr01++);
 374     outptr1[RGB_RED]   = range_limit[y + cred];
 375     outptr1[RGB_GREEN] = range_limit[y + cgreen];
 376     outptr1[RGB_BLUE]  = range_limit[y + cblue];
 377     outptr1 += RGB_PIXELSIZE;
 378     y  = GETJSAMPLE(*inptr01++);
 379     outptr1[RGB_RED]   = range_limit[y + cred];
 380     outptr1[RGB_GREEN] = range_limit[y + cgreen];
 381     outptr1[RGB_BLUE]  = range_limit[y + cblue];
 382     outptr1 += RGB_PIXELSIZE;
 383   }
 384   /* If image width is odd, do the last output column separately */
 385   if (cinfo->output_width & 1) {
 386     cb = GETJSAMPLE(*inptr1);
 387     cr = GETJSAMPLE(*inptr2);
 388     cred   = Crrtab[cr];
 389     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
 390     cblue  = Cbbtab[cb];
 391     y  = GETJSAMPLE(*inptr00);
 392     outptr0[RGB_RED]   = range_limit[y + cred];
 393     outptr0[RGB_GREEN] = range_limit[y + cgreen];
 394     outptr0[RGB_BLUE]  = range_limit[y + cblue];
 395     y  = GETJSAMPLE(*inptr01);
 396     outptr1[RGB_RED]   = range_limit[y + cred];
 397     outptr1[RGB_GREEN] = range_limit[y + cgreen];
 398     outptr1[RGB_BLUE]  = range_limit[y + cblue];
 399   }
 400 }
 401
 402
 403 /*
 404  * Module initialization routine for merged upsampling/color conversion.
 405  *
 406  * NB: this is called under the conditions determined by use_merged_upsample()
 407  * in jdmaster.c.  That routine MUST correspond to the actual capabilities
 408  * of this module; no safety checks are made here.
 409  */
 410
 411 GLOBAL(void)
 412 jinit_merged_upsampler (j_decompress_ptr cinfo)
 413 {
 414   my_upsample_ptr upsample;
 415
 416   upsample = (my_upsample_ptr)
 417     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 418                                 SIZEOF(my_upsampler));
 419   cinfo->upsample = &upsample->pub;
 420   upsample->pub.start_pass = start_pass_merged_upsample;
 421   upsample->pub.need_context_rows = FALSE;
 422
 423   upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
 424
 425   if (cinfo->max_v_samp_factor == 2) {
 426     upsample->pub.upsample = merged_2v_upsample;
 427     upsample->upmethod = h2v2_merged_upsample;
 428     /* Allocate a spare row buffer */
 429     upsample->spare_row = (JSAMPROW)
 430       (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 431                 (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
 432   } else {
 433     upsample->pub.upsample = merged_1v_upsample;
 434     upsample->upmethod = h2v1_merged_upsample;
 435     /* No spare row needed */
 436     upsample->spare_row = NULL;
 437   }
 438
 439   if (cinfo->jpeg_color_space == JCS_BG_YCC)
 440     build_bg_ycc_rgb_table(cinfo);
 441   else
 442     build_ycc_rgb_table(cinfo);
 443 }
 444
 445 #endif /* UPSAMPLE_MERGING_SUPPORTED */