reactos/dll/3rdparty/libjpeg/jdmerge.c

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