/src/FreeImage/Source/LibJPEG/jdmaster.c

  1/*
  2 * jdmaster.c
  3 *
  4 * Copyright (C) 1991-1997, Thomas G. Lane.
  5 * Modified 2002-2011 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
 22typedef 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
 36typedef 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
 44LOCAL(boolean)
 45use_merged_upsample (j_decompress_ptr cinfo)
 46{
 47#ifdef UPSAMPLE_MERGING_SUPPORTED
 48  /* Merging is the equivalent of plain box-filter upsampling */
 49  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
 50    return FALSE;
 51  /* jdmerge.c only supports YCC=>RGB color conversion */
 52  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
 53      cinfo->out_color_space != JCS_RGB ||
 54      cinfo->out_color_components != RGB_PIXELSIZE)
 55    return FALSE;
 56  /* and it only handles 2h1v or 2h2v sampling ratios */
 57  if (cinfo->comp_info[0].h_samp_factor != 2 ||
 58      cinfo->comp_info[1].h_samp_factor != 1 ||
 59      cinfo->comp_info[2].h_samp_factor != 1 ||
 60      cinfo->comp_info[0].v_samp_factor >  2 ||
 61      cinfo->comp_info[1].v_samp_factor != 1 ||
 62      cinfo->comp_info[2].v_samp_factor != 1)
 63    return FALSE;
 64  /* furthermore, it doesn't work if we've scaled the IDCTs differently */
 65  if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 66      cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 67      cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 68      cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
 69      cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
 70      cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size)
 71    return FALSE;
 72  /* ??? also need to test for upsample-time rescaling, when & if supported */
 73  return TRUE;			/* by golly, it'll work... */
 74#else
 75  return FALSE;
 76#endif
 77}
 78
 79
 80/*
 81 * Compute output image dimensions and related values.
 82 * NOTE: this is exported for possible use by application.
 83 * Hence it mustn't do anything that can't be done twice.
 84 * Also note that it may be called before the master module is initialized!
 85 */
 86
 87GLOBAL(void)
 88jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 89/* Do computations that are needed before master selection phase.
 90 * This function is used for full decompression.
 91 */
 92{
 93#ifdef IDCT_SCALING_SUPPORTED
 94  int ci;
 95  jpeg_component_info *compptr;
 96#endif
 97
 98  /* Prevent application from calling me at wrong times */
 99  if (cinfo->global_state != DSTATE_READY)
100    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
101
102  /* Compute core output image dimensions and DCT scaling choices. */
103  jpeg_core_output_dimensions(cinfo);
104
105#ifdef IDCT_SCALING_SUPPORTED
106
107  /* In selecting the actual DCT scaling for each component, we try to
108   * scale up the chroma components via IDCT scaling rather than upsampling.
109   * This saves time if the upsampler gets to use 1:1 scaling.
110   * Note this code adapts subsampling ratios which are powers of 2.
111   */
112  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
113       ci++, compptr++) {
114    int ssize = 1;
115    while (cinfo->min_DCT_h_scaled_size * ssize <=
116	   (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
117	   (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
118      ssize = ssize * 2;
119    }
120    compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
121    ssize = 1;
122    while (cinfo->min_DCT_v_scaled_size * ssize <=
123	   (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
124	   (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
125      ssize = ssize * 2;
126    }
127    compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
128
129    /* We don't support IDCT ratios larger than 2. */
130    if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
131	compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
132    else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
133	compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
134  }
135
136  /* Recompute downsampled dimensions of components;
137   * application needs to know these if using raw downsampled data.
138   */
139  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
140       ci++, compptr++) {
141    /* Size in samples, after IDCT scaling */
142    compptr->downsampled_width = (JDIMENSION)
143      jdiv_round_up((long) cinfo->image_width *
144		    (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
145		    (long) (cinfo->max_h_samp_factor * cinfo->block_size));
146    compptr->downsampled_height = (JDIMENSION)
147      jdiv_round_up((long) cinfo->image_height *
148		    (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
149		    (long) (cinfo->max_v_samp_factor * cinfo->block_size));
150  }
151
152#endif /* IDCT_SCALING_SUPPORTED */
153
154  /* Report number of components in selected colorspace. */
155  /* Probably this should be in the color conversion module... */
156  switch (cinfo->out_color_space) {
157  case JCS_GRAYSCALE:
158    cinfo->out_color_components = 1;
159    break;
160  case JCS_RGB:
161    cinfo->out_color_components = RGB_PIXELSIZE;
162    break;
163  case JCS_YCbCr:
164    cinfo->out_color_components = 3;
165    break;
166  case JCS_CMYK:
167  case JCS_YCCK:
168    cinfo->out_color_components = 4;
169    break;
170  default:			/* else must be same colorspace as in file */
171    cinfo->out_color_components = cinfo->num_components;
172    break;
173  }
174  cinfo->output_components = (cinfo->quantize_colors ? 1 :
175			      cinfo->out_color_components);
176
177  /* See if upsampler will want to emit more than one row at a time */
178  if (use_merged_upsample(cinfo))
179    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
180  else
181    cinfo->rec_outbuf_height = 1;
182}
183
184
185/*
186 * Several decompression processes need to range-limit values to the range
187 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
188 * due to noise introduced by quantization, roundoff error, etc.  These
189 * processes are inner loops and need to be as fast as possible.  On most
190 * machines, particularly CPUs with pipelines or instruction prefetch,
191 * a (subscript-check-less) C table lookup
192 *		x = sample_range_limit[x];
193 * is faster than explicit tests
194 *		if (x < 0)  x = 0;
195 *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
196 * These processes all use a common table prepared by the routine below.
197 *
198 * For most steps we can mathematically guarantee that the initial value
199 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
200 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
201 * limiting step (just after the IDCT), a wildly out-of-range value is 
202 * possible if the input data is corrupt.  To avoid any chance of indexing
203 * off the end of memory and getting a bad-pointer trap, we perform the
204 * post-IDCT limiting thus:
205 *		x = range_limit[x & MASK];
206 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
207 * samples.  Under normal circumstances this is more than enough range and
208 * a correct output will be generated; with bogus input data the mask will
209 * cause wraparound, and we will safely generate a bogus-but-in-range output.
210 * For the post-IDCT step, we want to convert the data from signed to unsigned
211 * representation by adding CENTERJSAMPLE at the same time that we limit it.
212 * So the post-IDCT limiting table ends up looking like this:
213 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
214 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
215 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
216 *   0,1,...,CENTERJSAMPLE-1
217 * Negative inputs select values from the upper half of the table after
218 * masking.
219 *
220 * We can save some space by overlapping the start of the post-IDCT table
221 * with the simpler range limiting table.  The post-IDCT table begins at
222 * sample_range_limit + CENTERJSAMPLE.
223 *
224 * Note that the table is allocated in near data space on PCs; it's small
225 * enough and used often enough to justify this.
226 */
227
228LOCAL(void)
229prepare_range_limit_table (j_decompress_ptr cinfo)
230/* Allocate and fill in the sample_range_limit table */
231{
232  JSAMPLE * table;
233  int i;
234
235  table = (JSAMPLE *)
236    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
237		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
238  table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */
239  cinfo->sample_range_limit = table;
240  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
241  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
242  /* Main part of "simple" table: limit[x] = x */
243  for (i = 0; i <= MAXJSAMPLE; i++)
244    table[i] = (JSAMPLE) i;
245  table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */
246  /* End of simple table, rest of first half of post-IDCT table */
247  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
248    table[i] = MAXJSAMPLE;
249  /* Second half of post-IDCT table */
250  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
251	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
252  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
253	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
254}
255
256
257/*
258 * Master selection of decompression modules.
259 * This is done once at jpeg_start_decompress time.  We determine
260 * which modules will be used and give them appropriate initialization calls.
261 * We also initialize the decompressor input side to begin consuming data.
262 *
263 * Since jpeg_read_header has finished, we know what is in the SOF
264 * and (first) SOS markers.  We also have all the application parameter
265 * settings.
266 */
267
268LOCAL(void)
269master_selection (j_decompress_ptr cinfo)
270{
271  my_master_ptr master = (my_master_ptr) cinfo->master;
272  boolean use_c_buffer;
273  long samplesperrow;
274  JDIMENSION jd_samplesperrow;
275
276  /* Initialize dimensions and other stuff */
277  jpeg_calc_output_dimensions(cinfo);
278  prepare_range_limit_table(cinfo);
279
280  /* Width of an output scanline must be representable as JDIMENSION. */
281  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
282  jd_samplesperrow = (JDIMENSION) samplesperrow;
283  if ((long) jd_samplesperrow != samplesperrow)
284    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
285
286  /* Initialize my private state */
287  master->pass_number = 0;
288  master->using_merged_upsample = use_merged_upsample(cinfo);
289
290  /* Color quantizer selection */
291  master->quantizer_1pass = NULL;
292  master->quantizer_2pass = NULL;
293  /* No mode changes if not using buffered-image mode. */
294  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
295    cinfo->enable_1pass_quant = FALSE;
296    cinfo->enable_external_quant = FALSE;
297    cinfo->enable_2pass_quant = FALSE;
298  }
299  if (cinfo->quantize_colors) {
300    if (cinfo->raw_data_out)
301      ERREXIT(cinfo, JERR_NOTIMPL);
302    /* 2-pass quantizer only works in 3-component color space. */
303    if (cinfo->out_color_components != 3) {
304      cinfo->enable_1pass_quant = TRUE;
305      cinfo->enable_external_quant = FALSE;
306      cinfo->enable_2pass_quant = FALSE;
307      cinfo->colormap = NULL;
308    } else if (cinfo->colormap != NULL) {
309      cinfo->enable_external_quant = TRUE;
310    } else if (cinfo->two_pass_quantize) {
311      cinfo->enable_2pass_quant = TRUE;
312    } else {
313      cinfo->enable_1pass_quant = TRUE;
314    }
315
316    if (cinfo->enable_1pass_quant) {
317#ifdef QUANT_1PASS_SUPPORTED
318      jinit_1pass_quantizer(cinfo);
319      master->quantizer_1pass = cinfo->cquantize;
320#else
321      ERREXIT(cinfo, JERR_NOT_COMPILED);
322#endif
323    }
324
325    /* We use the 2-pass code to map to external colormaps. */
326    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
327#ifdef QUANT_2PASS_SUPPORTED
328      jinit_2pass_quantizer(cinfo);
329      master->quantizer_2pass = cinfo->cquantize;
330#else
331      ERREXIT(cinfo, JERR_NOT_COMPILED);
332#endif
333    }
334    /* If both quantizers are initialized, the 2-pass one is left active;
335     * this is necessary for starting with quantization to an external map.
336     */
337  }
338
339  /* Post-processing: in particular, color conversion first */
340  if (! cinfo->raw_data_out) {
341    if (master->using_merged_upsample) {
342#ifdef UPSAMPLE_MERGING_SUPPORTED
343      jinit_merged_upsampler(cinfo); /* does color conversion too */
344#else
345      ERREXIT(cinfo, JERR_NOT_COMPILED);
346#endif
347    } else {
348      jinit_color_deconverter(cinfo);
349      jinit_upsampler(cinfo);
350    }
351    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
352  }
353  /* Inverse DCT */
354  jinit_inverse_dct(cinfo);
355  /* Entropy decoding: either Huffman or arithmetic coding. */
356  if (cinfo->arith_code)
357    jinit_arith_decoder(cinfo);
358  else {
359    jinit_huff_decoder(cinfo);
360  }
361
362  /* Initialize principal buffer controllers. */
363  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
364  jinit_d_coef_controller(cinfo, use_c_buffer);
365
366  if (! cinfo->raw_data_out)
367    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
368
369  /* We can now tell the memory manager to allocate virtual arrays. */
370  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
371
372  /* Initialize input side of decompressor to consume first scan. */
373  (*cinfo->inputctl->start_input_pass) (cinfo);
374
375#ifdef D_MULTISCAN_FILES_SUPPORTED
376  /* If jpeg_start_decompress will read the whole file, initialize
377   * progress monitoring appropriately.  The input step is counted
378   * as one pass.
379   */
380  if (cinfo->progress != NULL && ! cinfo->buffered_image &&
381      cinfo->inputctl->has_multiple_scans) {
382    int nscans;
383    /* Estimate number of scans to set pass_limit. */
384    if (cinfo->progressive_mode) {
385      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
386      nscans = 2 + 3 * cinfo->num_components;
387    } else {
388      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
389      nscans = cinfo->num_components;
390    }
391    cinfo->progress->pass_counter = 0L;
392    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
393    cinfo->progress->completed_passes = 0;
394    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
395    /* Count the input pass as done */
396    master->pass_number++;
397  }
398#endif /* D_MULTISCAN_FILES_SUPPORTED */
399}
400
401
402/*
403 * Per-pass setup.
404 * This is called at the beginning of each output pass.  We determine which
405 * modules will be active during this pass and give them appropriate
406 * start_pass calls.  We also set is_dummy_pass to indicate whether this
407 * is a "real" output pass or a dummy pass for color quantization.
408 * (In the latter case, jdapistd.c will crank the pass to completion.)
409 */
410
411METHODDEF(void)
412prepare_for_output_pass (j_decompress_ptr cinfo)
413{
414  my_master_ptr master = (my_master_ptr) cinfo->master;
415
416  if (master->pub.is_dummy_pass) {
417#ifdef QUANT_2PASS_SUPPORTED
418    /* Final pass of 2-pass quantization */
419    master->pub.is_dummy_pass = FALSE;
420    (*cinfo->cquantize->start_pass) (cinfo, FALSE);
421    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
422    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
423#else
424    ERREXIT(cinfo, JERR_NOT_COMPILED);
425#endif /* QUANT_2PASS_SUPPORTED */
426  } else {
427    if (cinfo->quantize_colors && cinfo->colormap == NULL) {
428      /* Select new quantization method */
429      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
430	cinfo->cquantize = master->quantizer_2pass;
431	master->pub.is_dummy_pass = TRUE;
432      } else if (cinfo->enable_1pass_quant) {
433	cinfo->cquantize = master->quantizer_1pass;
434      } else {
435	ERREXIT(cinfo, JERR_MODE_CHANGE);
436      }
437    }
438    (*cinfo->idct->start_pass) (cinfo);
439    (*cinfo->coef->start_output_pass) (cinfo);
440    if (! cinfo->raw_data_out) {
441      if (! master->using_merged_upsample)
442	(*cinfo->cconvert->start_pass) (cinfo);
443      (*cinfo->upsample->start_pass) (cinfo);
444      if (cinfo->quantize_colors)
445	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
446      (*cinfo->post->start_pass) (cinfo,
447	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
448      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
449    }
450  }
451
452  /* Set up progress monitor's pass info if present */
453  if (cinfo->progress != NULL) {
454    cinfo->progress->completed_passes = master->pass_number;
455    cinfo->progress->total_passes = master->pass_number +
456				    (master->pub.is_dummy_pass ? 2 : 1);
457    /* In buffered-image mode, we assume one more output pass if EOI not
458     * yet reached, but no more passes if EOI has been reached.
459     */
460    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
461      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
462    }
463  }
464}
465
466
467/*
468 * Finish up at end of an output pass.
469 */
470
471METHODDEF(void)
472finish_output_pass (j_decompress_ptr cinfo)
473{
474  my_master_ptr master = (my_master_ptr) cinfo->master;
475
476  if (cinfo->quantize_colors)
477    (*cinfo->cquantize->finish_pass) (cinfo);
478  master->pass_number++;
479}
480
481
482#ifdef D_MULTISCAN_FILES_SUPPORTED
483
484/*
485 * Switch to a new external colormap between output passes.
486 */
487
488GLOBAL(void)
489jpeg_new_colormap (j_decompress_ptr cinfo)
490{
491  my_master_ptr master = (my_master_ptr) cinfo->master;
492
493  /* Prevent application from calling me at wrong times */
494  if (cinfo->global_state != DSTATE_BUFIMAGE)
495    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
496
497  if (cinfo->quantize_colors && cinfo->enable_external_quant &&
498      cinfo->colormap != NULL) {
499    /* Select 2-pass quantizer for external colormap use */
500    cinfo->cquantize = master->quantizer_2pass;
501    /* Notify quantizer of colormap change */
502    (*cinfo->cquantize->new_color_map) (cinfo);
503    master->pub.is_dummy_pass = FALSE; /* just in case */
504  } else
505    ERREXIT(cinfo, JERR_MODE_CHANGE);
506}
507
508#endif /* D_MULTISCAN_FILES_SUPPORTED */
509
510
511/*
512 * Initialize master decompression control and select active modules.
513 * This is performed at the start of jpeg_start_decompress.
514 */
515
516GLOBAL(void)
517jinit_master_decompress (j_decompress_ptr cinfo)
518{
519  my_master_ptr master;
520
521  master = (my_master_ptr)
522      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
523				  SIZEOF(my_decomp_master));
524  cinfo->master = (struct jpeg_decomp_master *) master;
525  master->pub.prepare_for_output_pass = prepare_for_output_pass;
526  master->pub.finish_output_pass = finish_output_pass;
527
528  master->pub.is_dummy_pass = FALSE;
529
530  master_selection(cinfo);
531}