aboutsummaryrefslogtreecommitdiffstats
path: root/code/jpeg-6b/jcparam.c
blob: 6fc48f53653315537ffd098d83c25c0d3db502b5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
/*
 * jcparam.c
 *
 * Copyright (C) 1991-1998, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains optional default-setting code for the JPEG compressor.
 * Applications do not have to use this file, but those that don't use it
 * must know a lot more about the innards of the JPEG code.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Quantization table setup routines
 */

GLOBAL(void)
jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl,
		      const unsigned int *basic_table,
		      int scale_factor, boolean force_baseline)
/* Define a quantization table equal to the basic_table times
 * a scale factor (given as a percentage).
 * If force_baseline is TRUE, the computed quantization table entries
 * are limited to 1..255 for JPEG baseline compatibility.
 */
{
  JQUANT_TBL ** qtblptr;
  int i;
  long temp;

  /* Safety check to ensure start_compress not called yet. */
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS)
    ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl);

  qtblptr = & cinfo->quant_tbl_ptrs[which_tbl];

  if (*qtblptr == NULL)
    *qtblptr = jpeg_alloc_quant_table((j_common_ptr) cinfo);

  for (i = 0; i < DCTSIZE2; i++) {
    temp = ((long) basic_table[i] * scale_factor + 50L) / 100L;
    /* limit the values to the valid range */
    if (temp <= 0L) temp = 1L;
    if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */
    if (force_baseline && temp > 255L)
      temp = 255L;		/* limit to baseline range if requested */
    (*qtblptr)->quantval[i] = (UINT16) temp;
  }

  /* Initialize sent_table FALSE so table will be written to JPEG file. */
  (*qtblptr)->sent_table = FALSE;
}


GLOBAL(void)
jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor,
			 boolean force_baseline)
/* Set or change the 'quality' (quantization) setting, using default tables
 * and a straight percentage-scaling quality scale.  In most cases it's better
 * to use jpeg_set_quality (below); this entry point is provided for
 * applications that insist on a linear percentage scaling.
 */
{
  /* These are the sample quantization tables given in JPEG spec section K.1.
   * The spec says that the values given produce "good" quality, and
   * when divided by 2, "very good" quality.
   */
  static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
    16,  11,  10,  16,  24,  40,  51,  61,
    12,  12,  14,  19,  26,  58,  60,  55,
    14,  13,  16,  24,  40,  57,  69,  56,
    14,  17,  22,  29,  51,  87,  80,  62,
    18,  22,  37,  56,  68, 109, 103,  77,
    24,  35,  55,  64,  81, 104, 113,  92,
    49,  64,  78,  87, 103, 121, 120, 101,
    72,  92,  95,  98, 112, 100, 103,  99
  };
  static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
    17,  18,  24,  47,  99,  99,  99,  99,
    18,  21,  26,  66,  99,  99,  99,  99,
    24,  26,  56,  99,  99,  99,  99,  99,
    47,  66,  99,  99,  99,  99,  99,  99,
    99,  99,  99,  99,  99,  99,  99,  99,
    99,  99,  99,  99,  99,  99,  99,  99,
    99,  99,  99,  99,  99,  99,  99,  99,
    99,  99,  99,  99,  99,  99,  99,  99
  };

  /* Set up two quantization tables using the specified scaling */
  jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
		       scale_factor, force_baseline);
  jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
		       scale_factor, force_baseline);
}


GLOBAL(int)
jpeg_quality_scaling (int quality)
/* Convert a user-specified quality rating to a percentage scaling factor
 * for an underlying quantization table, using our recommended scaling curve.
 * The input 'quality' factor should be 0 (terrible) to 100 (very good).
 */
{
  /* Safety limit on quality factor.  Convert 0 to 1 to avoid zero divide. */
  if (quality <= 0) quality = 1;
  if (quality > 100) quality = 100;

  /* The basic table is used as-is (scaling 100) for a quality of 50.
   * Qualities 50..100 are converted to scaling percentage 200 - 2*Q;
   * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table
   * to make all the table entries 1 (hence, minimum quantization loss).
   * Qualities 1..50 are converted to scaling percentage 5000/Q.
   */
  if (quality < 50)
    quality = 5000 / quality;
  else
    quality = 200 - quality*2;

  return quality;
}


GLOBAL(void)
jpeg_set_quality (j_compress_ptr cinfo, int quality, boolean force_baseline)
/* Set or change the 'quality' (quantization) setting, using default tables.
 * This is the standard quality-adjusting entry point for typical user
 * interfaces; only those who want detailed control over quantization tables
 * would use the preceding three routines directly.
 */
{
  /* Convert user 0-100 rating to percentage scaling */
  quality = jpeg_quality_scaling(quality);

  /* Set up standard quality tables */
  jpeg_set_linear_quality(cinfo, quality, force_baseline);
}


/*
 * Huffman table setup routines
 */

LOCAL(void)
add_huff_table (j_compress_ptr cinfo,
		JHUFF_TBL **htblptr, const UINT8 *bits, const UINT8 *val)
/* Define a Huffman table */
{
  int nsymbols, len;

  if (*htblptr == NULL)
    *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);

  /* Copy the number-of-symbols-of-each-code-length counts */
  MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));

  /* Validate the counts.  We do this here mainly so we can copy the right
   * number of symbols from the val[] array, without risking marching off
   * the end of memory.  jchuff.c will do a more thorough test later.
   */
  nsymbols = 0;
  for (len = 1; len <= 16; len++)
    nsymbols += bits[len];
  if (nsymbols < 1 || nsymbols > 256)
    ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);

  MEMCOPY((*htblptr)->huffval, val, nsymbols * SIZEOF(UINT8));

  /* Initialize sent_table FALSE so table will be written to JPEG file. */
  (*htblptr)->sent_table = FALSE;
}


LOCAL(void)
std_huff_tables (j_compress_ptr cinfo)
/* Set up the standard Huffman tables (cf. JPEG standard section K.3) */
/* IMPORTANT: these are only valid for 8-bit data precision! */
{
  static const UINT8 bits_dc_luminance[17] =
    { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
  static const UINT8 val_dc_luminance[] =
    { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  
  static const UINT8 bits_dc_chrominance[17] =
    { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
  static const UINT8 val_dc_chrominance[] =
    { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
  
  static const UINT8 bits_ac_luminance[17] =
    { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
  static const UINT8 val_ac_luminance[] =
    { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
      0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
      0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
      0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
      0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
      0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
      0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
      0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
      0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
      0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
      0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
      0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
      0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
      0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
      0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
      0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
      0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
      0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
      0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
      0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa };
  
  static const UINT8 bits_ac_chrominance[17] =
    { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
  static const UINT8 val_ac_chrominance[] =
    { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
      0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
      0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
      0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
      0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
      0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
      0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
      0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
      0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
      0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
      0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
      0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
      0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
      0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
      0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
      0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
      0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
      0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
      0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
      0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa };
  
  add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[0],
		 bits_dc_luminance, val_dc_luminance);
  add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[0],
		 bits_ac_luminance, val_ac_luminance);
  add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[1],
		 bits_dc_chrominance, val_dc_chrominance);
  add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[1],
		 bits_ac_chrominance, val_ac_chrominance);
}


/*
 * Default parameter setup for compression.
 *
 * Applications that don't choose to use this routine must do their
 * own setup of all these parameters.  Alternately, you can call this
 * to establish defaults and then alter parameters selectively.  This
 * is the recommended approach since, if we add any new parameters,
 * your code will still work (they'll be set to reasonable defaults).
 */

GLOBAL(void)
jpeg_set_defaults (j_compress_ptr cinfo)
{
  int i;

  /* Safety check to ensure start_compress not called yet. */
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  /* Allocate comp_info array large enough for maximum component count.
   * Array is made permanent in case application wants to compress
   * multiple images at same param settings.
   */
  if (cinfo->comp_info == NULL)
    cinfo->comp_info = (jpeg_component_info *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
				  MAX_COMPONENTS * SIZEOF(jpeg_component_info));

  /* Initialize everything not dependent on the color space */

  cinfo->data_precision = BITS_IN_JSAMPLE;
  /* Set up two quantization tables using default quality of 75 */
  jpeg_set_quality(cinfo, 75, TRUE);
  /* Set up two Huffman tables */
  std_huff_tables(cinfo);

  /* Initialize default arithmetic coding conditioning */
  for (i = 0; i < NUM_ARITH_TBLS; i++) {
    cinfo->arith_dc_L[i] = 0;
    cinfo->arith_dc_U[i] = 1;
    cinfo->arith_ac_K[i] = 5;
  }

  /* Default is no multiple-scan output */
  cinfo->scan_info = NULL;
  cinfo->num_scans = 0;

  /* Expect normal source image, not raw downsampled data */
  cinfo->raw_data_in = FALSE;

  /* Use Huffman coding, not arithmetic coding, by default */
  cinfo->arith_code = FALSE;

  /* By default, don't do extra passes to optimize entropy coding */
  cinfo->optimize_coding = FALSE;
  /* The standard Huffman tables are only valid for 8-bit data precision.
   * If the precision is higher, force optimization on so that usable
   * tables will be computed.  This test can be removed if default tables
   * are supplied that are valid for the desired precision.
   */
  if (cinfo->data_precision > 8)
    cinfo->optimize_coding = TRUE;

  /* By default, use the simpler non-cosited sampling alignment */
  cinfo->CCIR601_sampling = FALSE;

  /* No input smoothing */
  cinfo->smoothing_factor = 0;

  /* DCT algorithm preference */
  cinfo->dct_method = JDCT_DEFAULT;

  /* No restart markers */
  cinfo->restart_interval = 0;
  cinfo->restart_in_rows = 0;

  /* Fill in default JFIF marker parameters.  Note that whether the marker
   * will actually be written is determined by jpeg_set_colorspace.
   *
   * By default, the library emits JFIF version code 1.01.
   * An application that wants to emit JFIF 1.02 extension markers should set
   * JFIF_minor_version to 2.  We could probably get away with just defaulting
   * to 1.02, but there may still be some decoders in use that will complain
   * about that; saying 1.01 should minimize compatibility problems.
   */
  cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */
  cinfo->JFIF_minor_version = 1;
  cinfo->density_unit = 0;	/* Pixel size is unknown by default */
  cinfo->X_density = 1;		/* Pixel aspect ratio is square by default */
  cinfo->Y_density = 1;

  /* Choose JPEG colorspace based on input space, set defaults accordingly */

  jpeg_default_colorspace(cinfo);
}


/*
 * Select an appropriate JPEG colorspace for in_color_space.
 */

GLOBAL(void)
jpeg_default_colorspace (j_compress_ptr cinfo)
{
  switch (cinfo->in_color_space) {
  case JCS_GRAYSCALE:
    jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
    break;
  case JCS_RGB:
    jpeg_set_colorspace(cinfo, JCS_YCbCr);
    break;
  case JCS_YCbCr:
    jpeg_set_colorspace(cinfo, JCS_YCbCr);
    break;
  case JCS_CMYK:
    jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */
    break;
  case JCS_YCCK:
    jpeg_set_colorspace(cinfo, JCS_YCCK);
    break;
  case JCS_UNKNOWN:
    jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
    break;
  default:
    ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
  }
}


/*
 * Set the JPEG colorspace, and choose colorspace-dependent default values.
 */

GLOBAL(void)
jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace)
{
  jpeg_component_info * compptr;
  int ci;

#define SET_COMP(index,id,hsamp,vsamp,quant,dctbl,actbl)  \
  (compptr = &cinfo->comp_info[index], \
   compptr->component_id = (id), \
   compptr->h_samp_factor = (hsamp), \
   compptr->v_samp_factor = (vsamp), \
   compptr->quant_tbl_no = (quant), \
   compptr->dc_tbl_no = (dctbl), \
   compptr->ac_tbl_no = (actbl) )

  /* Safety check to ensure start_compress not called yet. */
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
   * tables 1 for chrominance components.
   */

  cinfo->jpeg_color_space = colorspace;

  cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */
  cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */

  switch (colorspace) {
  case JCS_GRAYSCALE:
    cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
    cinfo->num_components = 1;
    /* JFIF specifies component ID 1 */
    SET_COMP(0, 1, 1,1, 0, 0,0);
    break;
  case JCS_RGB:
    cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */
    cinfo->num_components = 3;
    SET_COMP(0, 0x52 /* 'R' */, 1,1, 0, 0,0);
    SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0);
    SET_COMP(2, 0x42 /* 'B' */, 1,1, 0, 0,0);
    break;
  case JCS_YCbCr:
    cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
    cinfo->num_components = 3;
    /* JFIF specifies component IDs 1,2,3 */
    /* We default to 2x2 subsamples of chrominance */
    SET_COMP(0, 1, 2,2, 0, 0,0);
    SET_COMP(1, 2, 1,1, 1, 1,1);
    SET_COMP(2, 3, 1,1, 1, 1,1);
    break;
  case JCS_CMYK:
    cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */
    cinfo->num_components = 4;
    SET_COMP(0, 0x43 /* 'C' */, 1,1, 0, 0,0);
    SET_COMP(1, 0x4D /* 'M' */, 1,1, 0, 0,0);
    SET_COMP(2, 0x59 /* 'Y' */, 1,1, 0, 0,0);
    SET_COMP(3, 0x4B /* 'K' */, 1,1, 0, 0,0);
    break;
  case JCS_YCCK:
    cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */
    cinfo->num_components = 4;
    SET_COMP(0, 1, 2,2, 0, 0,0);
    SET_COMP(1, 2, 1,1, 1, 1,1);
    SET_COMP(2, 3, 1,1, 1, 1,1);
    SET_COMP(3, 4, 2,2, 0, 0,0);
    break;
  case JCS_UNKNOWN:
    cinfo->num_components = cinfo->input_components;
    if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS)
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
	       MAX_COMPONENTS);
    for (ci = 0; ci < cinfo->num_components; ci++) {
      SET_COMP(ci, ci, 1,1, 0, 0,0);
    }
    break;
  default:
    ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
  }
}


#ifdef C_PROGRESSIVE_SUPPORTED

LOCAL(jpeg_scan_info *)
fill_a_scan (jpeg_scan_info * scanptr, int ci,
	     int Ss, int Se, int Ah, int Al)
/* Support routine: generate one scan for specified component */
{
  scanptr->comps_in_scan = 1;
  scanptr->component_index[0] = ci;
  scanptr->Ss = Ss;
  scanptr->Se = Se;
  scanptr->Ah = Ah;
  scanptr->Al = Al;
  scanptr++;
  return scanptr;
}

LOCAL(jpeg_scan_info *)
fill_scans (jpeg_scan_info * scanptr, int ncomps,
	    int Ss, int Se, int Ah, int Al)
/* Support routine: generate one scan for each component */
{
  int ci;

  for (ci = 0; ci < ncomps; ci++) {
    scanptr->comps_in_scan = 1;
    scanptr->component_index[0] = ci;
    scanptr->Ss = Ss;
    scanptr->Se = Se;
    scanptr->Ah = Ah;
    scanptr->Al = Al;
    scanptr++;
  }
  return scanptr;
}

LOCAL(jpeg_scan_info *)
fill_dc_scans (jpeg_scan_info * scanptr, int ncomps, int Ah, int Al)
/* Support routine: generate interleaved DC scan if possible, else N scans */
{
  int ci;

  if (ncomps <= MAX_COMPS_IN_SCAN) {
    /* Single interleaved DC scan */
    scanptr->comps_in_scan = ncomps;
    for (ci = 0; ci < ncomps; ci++)
      scanptr->component_index[ci] = ci;
    scanptr->Ss = scanptr->Se = 0;
    scanptr->Ah = Ah;
    scanptr->Al = Al;
    scanptr++;
  } else {
    /* Noninterleaved DC scan for each component */
    scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al);
  }
  return scanptr;
}


/*
 * Create a recommended progressive-JPEG script.
 * cinfo->num_components and cinfo->jpeg_color_space must be correct.
 */

GLOBAL(void)
jpeg_simple_progression (j_compress_ptr cinfo)
{
  int ncomps = cinfo->num_components;
  int nscans;
  jpeg_scan_info * scanptr;

  /* Safety check to ensure start_compress not called yet. */
  if (cinfo->global_state != CSTATE_START)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  /* Figure space needed for script.  Calculation must match code below! */
  if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
    /* Custom script for YCbCr color images. */
    nscans = 10;
  } else {
    /* All-purpose script for other color spaces. */
    if (ncomps > MAX_COMPS_IN_SCAN)
      nscans = 6 * ncomps;	/* 2 DC + 4 AC scans per component */
    else
      nscans = 2 + 4 * ncomps;	/* 2 DC scans; 4 AC scans per component */
  }

  /* Allocate space for script.
   * We need to put it in the permanent pool in case the application performs
   * multiple compressions without changing the settings.  To avoid a memory
   * leak if jpeg_simple_progression is called repeatedly for the same JPEG
   * object, we try to re-use previously allocated space, and we allocate
   * enough space to handle YCbCr even if initially asked for grayscale.
   */
  if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) {
    cinfo->script_space_size = MAX(nscans, 10);
    cinfo->script_space = (jpeg_scan_info *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
			cinfo->script_space_size * SIZEOF(jpeg_scan_info));
  }
  scanptr = cinfo->script_space;
  cinfo->scan_info = scanptr;
  cinfo->num_scans = nscans;

  if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
    /* Custom script for YCbCr color images. */
    /* Initial DC scan */
    scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
    /* Initial AC scan: get some luma data out in a hurry */
    scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2);
    /* Chroma data is too small to be worth expending many scans on */
    scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1);
    scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1);
    /* Complete spectral selection for luma AC */
    scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2);
    /* Refine next bit of luma AC */
    scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1);
    /* Finish DC successive approximation */
    scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
    /* Finish AC successive approximation */
    scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0);
    scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0);
    /* Luma bottom bit comes last since it's usually largest scan */
    scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0);
  } else {
    /* All-purpose script for other color spaces. */
    /* Successive approximation first pass */
    scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
    scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2);
    scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2);
    /* Successive approximation second pass */
    scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1);
    /* Successive approximation final pass */
    scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
    scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0);
  }
}

#endif /* C_PROGRESSIVE_SUPPORTED */