1 /*
   2  * jdmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * Modified 2002-2017 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 master control logic for the JPEG decompressor.
  10  * These routines are concerned with selecting the modules to be executed
  11  * and with determining the number of passes and the work to be done in each
  12  * pass.
  13  */
  14 
  15 #define JPEG_INTERNALS
  16 #include "jinclude.h"
  17 #include "jpeglib.h"
  18 
  19 
  20 /* Private state */
  21 
  22 typedef struct {
  23   struct jpeg_decomp_master pub; /* public fields */
  24 
  25   int pass_number;              /* # of passes completed */
  26 
  27   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
  28 
  29   /* Saved references to initialized quantizer modules,
  30    * in case we need to switch modes.
  31    */
  32   struct jpeg_color_quantizer * quantizer_1pass;
  33   struct jpeg_color_quantizer * quantizer_2pass;
  34 } my_decomp_master;
  35 
  36 typedef my_decomp_master * my_master_ptr;
  37 
  38 
  39 /*
  40  * Determine whether merged upsample/color conversion should be used.
  41  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  42  */
  43 
  44 LOCAL(boolean)
  45 use_merged_upsample (j_decompress_ptr cinfo)
  46 {
  47 #ifdef UPSAMPLE_MERGING_SUPPORTED
  48   /* Merging is the equivalent of plain box-filter upsampling. */
  49   /* The following condition is only needed if fancy shall select
  50    * a different upsampling method.  In our current implementation
  51    * fancy only affects the DCT scaling, thus we can use fancy
  52    * upsampling and merged upsample simultaneously, in particular
  53    * with scaled DCT sizes larger than the default DCTSIZE.
  54    */
  55 #if 0
  56   if (cinfo->do_fancy_upsampling)
  57     return FALSE;
  58 #endif
  59   if (cinfo->CCIR601_sampling)
  60     return FALSE;
  61   /* jdmerge.c only supports YCC=>RGB color conversion */
  62   if ((cinfo->jpeg_color_space != JCS_YCbCr &&
  63        cinfo->jpeg_color_space != JCS_BG_YCC) ||
  64       cinfo->num_components != 3 ||
  65       cinfo->out_color_space != JCS_RGB ||
  66       cinfo->out_color_components != RGB_PIXELSIZE ||
  67       cinfo->color_transform)
  68     return FALSE;
  69   /* and it only handles 2h1v or 2h2v sampling ratios */
  70   if (cinfo->comp_info[0].h_samp_factor != 2 ||
  71       cinfo->comp_info[1].h_samp_factor != 1 ||
  72       cinfo->comp_info[2].h_samp_factor != 1 ||
  73       cinfo->comp_info[0].v_samp_factor >  2 ||
  74       cinfo->comp_info[1].v_samp_factor != 1 ||
  75       cinfo->comp_info[2].v_samp_factor != 1)
  76     return FALSE;
  77   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
  78   if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
  79       cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
  80       cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
  81       cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
  82       cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
  83       cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size)
  84     return FALSE;
  85   /* ??? also need to test for upsample-time rescaling, when & if supported */
  86   return TRUE;                  /* by golly, it'll work... */
  87 #else
  88   return FALSE;
  89 #endif
  90 }
  91 
  92 
  93 /*
  94  * Compute output image dimensions and related values.
  95  * NOTE: this is exported for possible use by application.
  96  * Hence it mustn't do anything that can't be done twice.
  97  * Also note that it may be called before the master module is initialized!
  98  */
  99 
 100 GLOBAL(void)
 101 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 102 /* Do computations that are needed before master selection phase.
 103  * This function is used for full decompression.
 104  */
 105 {
 106 #ifdef IDCT_SCALING_SUPPORTED
 107   int ci;
 108   jpeg_component_info *compptr;
 109 #endif
 110 
 111   /* Prevent application from calling me at wrong times */
 112   if (cinfo->global_state != DSTATE_READY)
 113     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 114 
 115   /* Compute core output image dimensions and DCT scaling choices. */
 116   jpeg_core_output_dimensions(cinfo);
 117 
 118 #ifdef IDCT_SCALING_SUPPORTED
 119 
 120   /* In selecting the actual DCT scaling for each component, we try to
 121    * scale up the chroma components via IDCT scaling rather than upsampling.
 122    * This saves time if the upsampler gets to use 1:1 scaling.
 123    * Note this code adapts subsampling ratios which are powers of 2.
 124    */
 125   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 126        ci++, compptr++) {
 127     int ssize = 1;
 128     while (cinfo->min_DCT_h_scaled_size * ssize <=
 129            (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
 130            (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
 131       ssize = ssize * 2;
 132     }
 133     compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
 134     ssize = 1;
 135     while (cinfo->min_DCT_v_scaled_size * ssize <=
 136            (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
 137            (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
 138       ssize = ssize * 2;
 139     }
 140     compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
 141 
 142     /* We don't support IDCT ratios larger than 2. */
 143     if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
 144         compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
 145     else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
 146         compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
 147   }
 148 
 149   /* Recompute downsampled dimensions of components;
 150    * application needs to know these if using raw downsampled data.
 151    */
 152   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 153        ci++, compptr++) {
 154     /* Size in samples, after IDCT scaling */
 155     compptr->downsampled_width = (JDIMENSION)
 156       jdiv_round_up((long) cinfo->image_width *
 157                     (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
 158                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 159     compptr->downsampled_height = (JDIMENSION)
 160       jdiv_round_up((long) cinfo->image_height *
 161                     (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
 162                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 163   }
 164 
 165 #endif /* IDCT_SCALING_SUPPORTED */
 166 
 167   /* Report number of components in selected colorspace. */
 168   /* Probably this should be in the color conversion module... */
 169   switch (cinfo->out_color_space) {
 170   case JCS_GRAYSCALE:
 171     cinfo->out_color_components = 1;
 172     break;
 173   case JCS_RGB:
 174   case JCS_BG_RGB:
 175     cinfo->out_color_components = RGB_PIXELSIZE;
 176     break;
 177   case JCS_YCbCr:
 178   case JCS_BG_YCC:
 179     cinfo->out_color_components = 3;
 180     break;
 181   case JCS_CMYK:
 182   case JCS_YCCK:
 183     cinfo->out_color_components = 4;
 184     break;
 185   default:                      /* else must be same colorspace as in file */
 186     cinfo->out_color_components = cinfo->num_components;
 187     break;
 188   }
 189   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 190                               cinfo->out_color_components);
 191 
 192   /* See if upsampler will want to emit more than one row at a time */
 193   if (use_merged_upsample(cinfo))
 194     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
 195   else
 196     cinfo->rec_outbuf_height = 1;
 197 }
 198 
 199 
 200 /*
 201  * Several decompression processes need to range-limit values to the range
 202  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 203  * due to noise introduced by quantization, roundoff error, etc.  These
 204  * processes are inner loops and need to be as fast as possible.  On most
 205  * machines, particularly CPUs with pipelines or instruction prefetch,
 206  * a (subscript-check-less) C table lookup
 207  *              x = sample_range_limit[x];
 208  * is faster than explicit tests
 209  *              if (x < 0)  x = 0;
 210  *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 211  * These processes all use a common table prepared by the routine below.
 212  *
 213  * For most steps we can mathematically guarantee that the initial value
 214  * of x is within 2*(MAXJSAMPLE+1) of the legal range, so a table running
 215  * from -2*(MAXJSAMPLE+1) to 3*MAXJSAMPLE+2 is sufficient.  But for the
 216  * initial limiting step (just after the IDCT), a wildly out-of-range value
 217  * is possible if the input data is corrupt.  To avoid any chance of indexing
 218  * off the end of memory and getting a bad-pointer trap, we perform the
 219  * post-IDCT limiting thus:
 220  *              x = (sample_range_limit - SUBSET)[(x + CENTER) & MASK];
 221  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 222  * samples.  Under normal circumstances this is more than enough range and
 223  * a correct output will be generated; with bogus input data the mask will
 224  * cause wraparound, and we will safely generate a bogus-but-in-range output.
 225  * For the post-IDCT step, we want to convert the data from signed to unsigned
 226  * representation by adding CENTERJSAMPLE at the same time that we limit it.
 227  * This is accomplished with SUBSET = CENTER - CENTERJSAMPLE.
 228  *
 229  * Note that the table is allocated in near data space on PCs; it's small
 230  * enough and used often enough to justify this.
 231  */
 232 
 233 LOCAL(void)
 234 prepare_range_limit_table (j_decompress_ptr cinfo)
 235 /* Allocate and fill in the sample_range_limit table */
 236 {
 237   JSAMPLE * table;
 238   int i;
 239 
 240   table = (JSAMPLE *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo,
 241     JPOOL_IMAGE, (RANGE_CENTER * 2 + MAXJSAMPLE + 1) * SIZEOF(JSAMPLE));
 242   /* First segment of range limit table: limit[x] = 0 for x < 0 */
 243   MEMZERO(table, RANGE_CENTER * SIZEOF(JSAMPLE));
 244   table += RANGE_CENTER;        /* allow negative subscripts of table */
 245   cinfo->sample_range_limit = table;
 246   /* Main part of range limit table: limit[x] = x */
 247   for (i = 0; i <= MAXJSAMPLE; i++)
 248     table[i] = (JSAMPLE) i;
 249   /* End of range limit table: limit[x] = MAXJSAMPLE for x > MAXJSAMPLE */
 250   for (; i <=  MAXJSAMPLE + RANGE_CENTER; i++)
 251     table[i] = MAXJSAMPLE;
 252 }
 253 
 254 
 255 /*
 256  * Master selection of decompression modules.
 257  * This is done once at jpeg_start_decompress time.  We determine
 258  * which modules will be used and give them appropriate initialization calls.
 259  * We also initialize the decompressor input side to begin consuming data.
 260  *
 261  * Since jpeg_read_header has finished, we know what is in the SOF
 262  * and (first) SOS markers.  We also have all the application parameter
 263  * settings.
 264  */
 265 
 266 LOCAL(void)
 267 master_selection (j_decompress_ptr cinfo)
 268 {
 269   my_master_ptr master = (my_master_ptr) cinfo->master;
 270   boolean use_c_buffer;
 271   long samplesperrow;
 272   JDIMENSION jd_samplesperrow;
 273 
 274   /* For now, precision must match compiled-in value... */
 275   if (cinfo->data_precision != BITS_IN_JSAMPLE)
 276     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
 277 
 278   /* Initialize dimensions and other stuff */
 279   jpeg_calc_output_dimensions(cinfo);
 280   prepare_range_limit_table(cinfo);
 281 
 282   /* Sanity check on image dimensions */
 283   if (cinfo->output_height <= 0 || cinfo->output_width <= 0 ||
 284       cinfo->out_color_components <= 0)
 285     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
 286 
 287   /* Width of an output scanline must be representable as JDIMENSION. */
 288   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
 289   jd_samplesperrow = (JDIMENSION) samplesperrow;
 290   if ((long) jd_samplesperrow != samplesperrow)
 291     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 292 
 293   /* Initialize my private state */
 294   master->pass_number = 0;
 295   master->using_merged_upsample = use_merged_upsample(cinfo);
 296 
 297   /* Color quantizer selection */
 298   master->quantizer_1pass = NULL;
 299   master->quantizer_2pass = NULL;
 300   /* No mode changes if not using buffered-image mode. */
 301   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
 302     cinfo->enable_1pass_quant = FALSE;
 303     cinfo->enable_external_quant = FALSE;
 304     cinfo->enable_2pass_quant = FALSE;
 305   }
 306   if (cinfo->quantize_colors) {
 307     if (cinfo->raw_data_out)
 308       ERREXIT(cinfo, JERR_NOTIMPL);
 309     /* 2-pass quantizer only works in 3-component color space. */
 310     if (cinfo->out_color_components != 3) {
 311       cinfo->enable_1pass_quant = TRUE;
 312       cinfo->enable_external_quant = FALSE;
 313       cinfo->enable_2pass_quant = FALSE;
 314       cinfo->colormap = NULL;
 315     } else if (cinfo->colormap != NULL) {
 316       cinfo->enable_external_quant = TRUE;
 317     } else if (cinfo->two_pass_quantize) {
 318       cinfo->enable_2pass_quant = TRUE;
 319     } else {
 320       cinfo->enable_1pass_quant = TRUE;
 321     }
 322 
 323     if (cinfo->enable_1pass_quant) {
 324 #ifdef QUANT_1PASS_SUPPORTED
 325       jinit_1pass_quantizer(cinfo);
 326       master->quantizer_1pass = cinfo->cquantize;
 327 #else
 328       ERREXIT(cinfo, JERR_NOT_COMPILED);
 329 #endif
 330     }
 331 
 332     /* We use the 2-pass code to map to external colormaps. */
 333     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 334 #ifdef QUANT_2PASS_SUPPORTED
 335       jinit_2pass_quantizer(cinfo);
 336       master->quantizer_2pass = cinfo->cquantize;
 337 #else
 338       ERREXIT(cinfo, JERR_NOT_COMPILED);
 339 #endif
 340     }
 341     /* If both quantizers are initialized, the 2-pass one is left active;
 342      * this is necessary for starting with quantization to an external map.
 343      */
 344   }
 345 
 346   /* Post-processing: in particular, color conversion first */
 347   if (! cinfo->raw_data_out) {
 348     if (master->using_merged_upsample) {
 349 #ifdef UPSAMPLE_MERGING_SUPPORTED
 350       jinit_merged_upsampler(cinfo); /* does color conversion too */
 351 #else
 352       ERREXIT(cinfo, JERR_NOT_COMPILED);
 353 #endif
 354     } else {
 355       jinit_color_deconverter(cinfo);
 356       jinit_upsampler(cinfo);
 357     }
 358     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
 359   }
 360   /* Inverse DCT */
 361   jinit_inverse_dct(cinfo);
 362   /* Entropy decoding: either Huffman or arithmetic coding. */
 363   if (cinfo->arith_code) {
 364     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 365   } else {
 366     jinit_huff_decoder(cinfo);
 367   }
 368 
 369   /* Initialize principal buffer controllers. */
 370   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
 371   jinit_d_coef_controller(cinfo, use_c_buffer);
 372 
 373   if (! cinfo->raw_data_out)
 374     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
 375 
 376   /* We can now tell the memory manager to allocate virtual arrays. */
 377   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
 378 
 379   /* Initialize input side of decompressor to consume first scan. */
 380   (*cinfo->inputctl->start_input_pass) (cinfo);
 381 
 382 #ifdef D_MULTISCAN_FILES_SUPPORTED
 383   /* If jpeg_start_decompress will read the whole file, initialize
 384    * progress monitoring appropriately.  The input step is counted
 385    * as one pass.
 386    */
 387   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
 388       cinfo->inputctl->has_multiple_scans) {
 389     int nscans;
 390     /* Estimate number of scans to set pass_limit. */
 391     if (cinfo->progressive_mode) {
 392       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
 393       nscans = 2 + 3 * cinfo->num_components;
 394     } else {
 395       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
 396       nscans = cinfo->num_components;
 397     }
 398     cinfo->progress->pass_counter = 0L;
 399     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
 400     cinfo->progress->completed_passes = 0;
 401     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
 402     /* Count the input pass as done */
 403     master->pass_number++;
 404   }
 405 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 406 }
 407 
 408 
 409 /*
 410  * Per-pass setup.
 411  * This is called at the beginning of each output pass.  We determine which
 412  * modules will be active during this pass and give them appropriate
 413  * start_pass calls.  We also set is_dummy_pass to indicate whether this
 414  * is a "real" output pass or a dummy pass for color quantization.
 415  * (In the latter case, jdapistd.c will crank the pass to completion.)
 416  */
 417 
 418 METHODDEF(void)
 419 prepare_for_output_pass (j_decompress_ptr cinfo)
 420 {
 421   my_master_ptr master = (my_master_ptr) cinfo->master;
 422 
 423   if (master->pub.is_dummy_pass) {
 424 #ifdef QUANT_2PASS_SUPPORTED
 425     /* Final pass of 2-pass quantization */
 426     master->pub.is_dummy_pass = FALSE;
 427     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
 428     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
 429     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 430 #else
 431     ERREXIT(cinfo, JERR_NOT_COMPILED);
 432 #endif /* QUANT_2PASS_SUPPORTED */
 433   } else {
 434     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
 435       /* Select new quantization method */
 436       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 437         cinfo->cquantize = master->quantizer_2pass;
 438         master->pub.is_dummy_pass = TRUE;
 439       } else if (cinfo->enable_1pass_quant) {
 440         cinfo->cquantize = master->quantizer_1pass;
 441       } else {
 442         ERREXIT(cinfo, JERR_MODE_CHANGE);
 443       }
 444     }
 445     (*cinfo->idct->start_pass) (cinfo);
 446     (*cinfo->coef->start_output_pass) (cinfo);
 447     if (! cinfo->raw_data_out) {
 448       if (! master->using_merged_upsample)
 449         (*cinfo->cconvert->start_pass) (cinfo);
 450       (*cinfo->upsample->start_pass) (cinfo);
 451       if (cinfo->quantize_colors)
 452         (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
 453       (*cinfo->post->start_pass) (cinfo,
 454             (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 455       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 456     }
 457   }
 458 
 459   /* Set up progress monitor's pass info if present */
 460   if (cinfo->progress != NULL) {
 461     cinfo->progress->completed_passes = master->pass_number;
 462     cinfo->progress->total_passes = master->pass_number +
 463                                     (master->pub.is_dummy_pass ? 2 : 1);
 464     /* In buffered-image mode, we assume one more output pass if EOI not
 465      * yet reached, but no more passes if EOI has been reached.
 466      */
 467     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
 468       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
 469     }
 470   }
 471 }
 472 
 473 
 474 /*
 475  * Finish up at end of an output pass.
 476  */
 477 
 478 METHODDEF(void)
 479 finish_output_pass (j_decompress_ptr cinfo)
 480 {
 481   my_master_ptr master = (my_master_ptr) cinfo->master;
 482 
 483   if (cinfo->quantize_colors)
 484     (*cinfo->cquantize->finish_pass) (cinfo);
 485   master->pass_number++;
 486 }
 487 
 488 
 489 #ifdef D_MULTISCAN_FILES_SUPPORTED
 490 
 491 /*
 492  * Switch to a new external colormap between output passes.
 493  */
 494 
 495 GLOBAL(void)
 496 jpeg_new_colormap (j_decompress_ptr cinfo)
 497 {
 498   my_master_ptr master = (my_master_ptr) cinfo->master;
 499 
 500   /* Prevent application from calling me at wrong times */
 501   if (cinfo->global_state != DSTATE_BUFIMAGE)
 502     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 503 
 504   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
 505       cinfo->colormap != NULL) {
 506     /* Select 2-pass quantizer for external colormap use */
 507     cinfo->cquantize = master->quantizer_2pass;
 508     /* Notify quantizer of colormap change */
 509     (*cinfo->cquantize->new_color_map) (cinfo);
 510     master->pub.is_dummy_pass = FALSE; /* just in case */
 511   } else
 512     ERREXIT(cinfo, JERR_MODE_CHANGE);
 513 }
 514 
 515 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 516 
 517 
 518 /*
 519  * Initialize master decompression control and select active modules.
 520  * This is performed at the start of jpeg_start_decompress.
 521  */
 522 
 523 GLOBAL(void)
 524 jinit_master_decompress (j_decompress_ptr cinfo)
 525 {
 526   my_master_ptr master;
 527 
 528   master = (my_master_ptr)
 529       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 530                                   SIZEOF(my_decomp_master));
 531   cinfo->master = &master->pub;
 532   master->pub.prepare_for_output_pass = prepare_for_output_pass;
 533   master->pub.finish_output_pass = finish_output_pass;
 534 
 535   master->pub.is_dummy_pass = FALSE;
 536 
 537   master_selection(cinfo);
 538 }