1/*
2 * jcparam.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1998, Thomas G. Lane.
6 * Modified 2003-2008 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2009-2011, 2018, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
11 *
12 * This file contains optional default-setting code for the JPEG compressor.
13 * Applications do not have to use this file, but those that don't use it
14 * must know a lot more about the innards of the JPEG code.
15 */
16
17#define JPEG_INTERNALS
18#include "jinclude.h"
19#include "jpeglib.h"
20#include "jstdhuff.c"
21
22
23/*
24 * Quantization table setup routines
25 */
26
27GLOBAL(void)
28jpeg_add_quant_table(j_compress_ptr cinfo, int which_tbl,
29 const unsigned int *basic_table, int scale_factor,
30 boolean force_baseline)
31/* Define a quantization table equal to the basic_table times
32 * a scale factor (given as a percentage).
33 * If force_baseline is TRUE, the computed quantization table entries
34 * are limited to 1..255 for JPEG baseline compatibility.
35 */
36{
37 JQUANT_TBL **qtblptr;
38 int i;
39 long temp;
40
41 /* Safety check to ensure start_compress not called yet. */
42 if (cinfo->global_state != CSTATE_START)
43 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
44
45 if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS)
46 ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl);
47
48 qtblptr = &cinfo->quant_tbl_ptrs[which_tbl];
49
50 if (*qtblptr == NULL)
51 *qtblptr = jpeg_alloc_quant_table((j_common_ptr)cinfo);
52
53 for (i = 0; i < DCTSIZE2; i++) {
54 temp = ((long)basic_table[i] * scale_factor + 50L) / 100L;
55 /* limit the values to the valid range */
56 if (temp <= 0L) temp = 1L;
57 if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */
58 if (force_baseline && temp > 255L)
59 temp = 255L; /* limit to baseline range if requested */
60 (*qtblptr)->quantval[i] = (UINT16)temp;
61 }
62
63 /* Initialize sent_table FALSE so table will be written to JPEG file. */
64 (*qtblptr)->sent_table = FALSE;
65}
66
67
68/* These are the sample quantization tables given in Annex K (Clause K.1) of
69 * Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
70 * The spec says that the values given produce "good" quality, and
71 * when divided by 2, "very good" quality.
72 */
73static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
74 16, 11, 10, 16, 24, 40, 51, 61,
75 12, 12, 14, 19, 26, 58, 60, 55,
76 14, 13, 16, 24, 40, 57, 69, 56,
77 14, 17, 22, 29, 51, 87, 80, 62,
78 18, 22, 37, 56, 68, 109, 103, 77,
79 24, 35, 55, 64, 81, 104, 113, 92,
80 49, 64, 78, 87, 103, 121, 120, 101,
81 72, 92, 95, 98, 112, 100, 103, 99
82};
83static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
84 17, 18, 24, 47, 99, 99, 99, 99,
85 18, 21, 26, 66, 99, 99, 99, 99,
86 24, 26, 56, 99, 99, 99, 99, 99,
87 47, 66, 99, 99, 99, 99, 99, 99,
88 99, 99, 99, 99, 99, 99, 99, 99,
89 99, 99, 99, 99, 99, 99, 99, 99,
90 99, 99, 99, 99, 99, 99, 99, 99,
91 99, 99, 99, 99, 99, 99, 99, 99
92};
93
94
95#if JPEG_LIB_VERSION >= 70
96GLOBAL(void)
97jpeg_default_qtables(j_compress_ptr cinfo, boolean force_baseline)
98/* Set or change the 'quality' (quantization) setting, using default tables
99 * and straight percentage-scaling quality scales.
100 * This entry point allows different scalings for luminance and chrominance.
101 */
102{
103 /* Set up two quantization tables using the specified scaling */
104 jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
105 cinfo->q_scale_factor[0], force_baseline);
106 jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
107 cinfo->q_scale_factor[1], force_baseline);
108}
109#endif
110
111
112GLOBAL(void)
113jpeg_set_linear_quality(j_compress_ptr cinfo, int scale_factor,
114 boolean force_baseline)
115/* Set or change the 'quality' (quantization) setting, using default tables
116 * and a straight percentage-scaling quality scale. In most cases it's better
117 * to use jpeg_set_quality (below); this entry point is provided for
118 * applications that insist on a linear percentage scaling.
119 */
120{
121 /* Set up two quantization tables using the specified scaling */
122 jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
123 scale_factor, force_baseline);
124 jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
125 scale_factor, force_baseline);
126}
127
128
129GLOBAL(int)
130jpeg_quality_scaling(int quality)
131/* Convert a user-specified quality rating to a percentage scaling factor
132 * for an underlying quantization table, using our recommended scaling curve.
133 * The input 'quality' factor should be 0 (terrible) to 100 (very good).
134 */
135{
136 /* Safety limit on quality factor. Convert 0 to 1 to avoid zero divide. */
137 if (quality <= 0) quality = 1;
138 if (quality > 100) quality = 100;
139
140 /* The basic table is used as-is (scaling 100) for a quality of 50.
141 * Qualities 50..100 are converted to scaling percentage 200 - 2*Q;
142 * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table
143 * to make all the table entries 1 (hence, minimum quantization loss).
144 * Qualities 1..50 are converted to scaling percentage 5000/Q.
145 */
146 if (quality < 50)
147 quality = 5000 / quality;
148 else
149 quality = 200 - quality * 2;
150
151 return quality;
152}
153
154
155GLOBAL(void)
156jpeg_set_quality(j_compress_ptr cinfo, int quality, boolean force_baseline)
157/* Set or change the 'quality' (quantization) setting, using default tables.
158 * This is the standard quality-adjusting entry point for typical user
159 * interfaces; only those who want detailed control over quantization tables
160 * would use the preceding three routines directly.
161 */
162{
163 /* Convert user 0-100 rating to percentage scaling */
164 quality = jpeg_quality_scaling(quality);
165
166 /* Set up standard quality tables */
167 jpeg_set_linear_quality(cinfo, quality, force_baseline);
168}
169
170
171/*
172 * Default parameter setup for compression.
173 *
174 * Applications that don't choose to use this routine must do their
175 * own setup of all these parameters. Alternately, you can call this
176 * to establish defaults and then alter parameters selectively. This
177 * is the recommended approach since, if we add any new parameters,
178 * your code will still work (they'll be set to reasonable defaults).
179 */
180
181GLOBAL(void)
182jpeg_set_defaults(j_compress_ptr cinfo)
183{
184 int i;
185
186 /* Safety check to ensure start_compress not called yet. */
187 if (cinfo->global_state != CSTATE_START)
188 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
189
190 /* Allocate comp_info array large enough for maximum component count.
191 * Array is made permanent in case application wants to compress
192 * multiple images at same param settings.
193 */
194 if (cinfo->comp_info == NULL)
195 cinfo->comp_info = (jpeg_component_info *)
196 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
197 MAX_COMPONENTS * sizeof(jpeg_component_info));
198
199 /* Initialize everything not dependent on the color space */
200
201#if JPEG_LIB_VERSION >= 70
202 cinfo->scale_num = 1; /* 1:1 scaling */
203 cinfo->scale_denom = 1;
204#endif
205 cinfo->data_precision = BITS_IN_JSAMPLE;
206 /* Set up two quantization tables using default quality of 75 */
207 jpeg_set_quality(cinfo, 75, TRUE);
208 /* Set up two Huffman tables */
209 std_huff_tables((j_common_ptr)cinfo);
210
211 /* Initialize default arithmetic coding conditioning */
212 for (i = 0; i < NUM_ARITH_TBLS; i++) {
213 cinfo->arith_dc_L[i] = 0;
214 cinfo->arith_dc_U[i] = 1;
215 cinfo->arith_ac_K[i] = 5;
216 }
217
218 /* Default is no multiple-scan output */
219 cinfo->scan_info = NULL;
220 cinfo->num_scans = 0;
221
222 /* Expect normal source image, not raw downsampled data */
223 cinfo->raw_data_in = FALSE;
224
225 /* Use Huffman coding, not arithmetic coding, by default */
226 cinfo->arith_code = FALSE;
227
228 /* By default, don't do extra passes to optimize entropy coding */
229 cinfo->optimize_coding = FALSE;
230 /* The standard Huffman tables are only valid for 8-bit data precision.
231 * If the precision is higher, force optimization on so that usable
232 * tables will be computed. This test can be removed if default tables
233 * are supplied that are valid for the desired precision.
234 */
235 if (cinfo->data_precision > 8)
236 cinfo->optimize_coding = TRUE;
237
238 /* By default, use the simpler non-cosited sampling alignment */
239 cinfo->CCIR601_sampling = FALSE;
240
241#if JPEG_LIB_VERSION >= 70
242 /* By default, apply fancy downsampling */
243 cinfo->do_fancy_downsampling = TRUE;
244#endif
245
246 /* No input smoothing */
247 cinfo->smoothing_factor = 0;
248
249 /* DCT algorithm preference */
250 cinfo->dct_method = JDCT_DEFAULT;
251
252 /* No restart markers */
253 cinfo->restart_interval = 0;
254 cinfo->restart_in_rows = 0;
255
256 /* Fill in default JFIF marker parameters. Note that whether the marker
257 * will actually be written is determined by jpeg_set_colorspace.
258 *
259 * By default, the library emits JFIF version code 1.01.
260 * An application that wants to emit JFIF 1.02 extension markers should set
261 * JFIF_minor_version to 2. We could probably get away with just defaulting
262 * to 1.02, but there may still be some decoders in use that will complain
263 * about that; saying 1.01 should minimize compatibility problems.
264 */
265 cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */
266 cinfo->JFIF_minor_version = 1;
267 cinfo->density_unit = 0; /* Pixel size is unknown by default */
268 cinfo->X_density = 1; /* Pixel aspect ratio is square by default */
269 cinfo->Y_density = 1;
270
271 /* Choose JPEG colorspace based on input space, set defaults accordingly */
272
273 jpeg_default_colorspace(cinfo);
274}
275
276
277/*
278 * Select an appropriate JPEG colorspace for in_color_space.
279 */
280
281GLOBAL(void)
282jpeg_default_colorspace(j_compress_ptr cinfo)
283{
284 switch (cinfo->in_color_space) {
285 case JCS_GRAYSCALE:
286 jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
287 break;
288 case JCS_RGB:
289 case JCS_EXT_RGB:
290 case JCS_EXT_RGBX:
291 case JCS_EXT_BGR:
292 case JCS_EXT_BGRX:
293 case JCS_EXT_XBGR:
294 case JCS_EXT_XRGB:
295 case JCS_EXT_RGBA:
296 case JCS_EXT_BGRA:
297 case JCS_EXT_ABGR:
298 case JCS_EXT_ARGB:
299 jpeg_set_colorspace(cinfo, JCS_YCbCr);
300 break;
301 case JCS_YCbCr:
302 jpeg_set_colorspace(cinfo, JCS_YCbCr);
303 break;
304 case JCS_CMYK:
305 jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */
306 break;
307 case JCS_YCCK:
308 jpeg_set_colorspace(cinfo, JCS_YCCK);
309 break;
310 case JCS_UNKNOWN:
311 jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
312 break;
313 default:
314 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
315 }
316}
317
318
319/*
320 * Set the JPEG colorspace, and choose colorspace-dependent default values.
321 */
322
323GLOBAL(void)
324jpeg_set_colorspace(j_compress_ptr cinfo, J_COLOR_SPACE colorspace)
325{
326 jpeg_component_info *compptr;
327 int ci;
328
329#define SET_COMP(index, id, hsamp, vsamp, quant, dctbl, actbl) \
330 (compptr = &cinfo->comp_info[index], \
331 compptr->component_id = (id), \
332 compptr->h_samp_factor = (hsamp), \
333 compptr->v_samp_factor = (vsamp), \
334 compptr->quant_tbl_no = (quant), \
335 compptr->dc_tbl_no = (dctbl), \
336 compptr->ac_tbl_no = (actbl) )
337
338 /* Safety check to ensure start_compress not called yet. */
339 if (cinfo->global_state != CSTATE_START)
340 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
341
342 /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
343 * tables 1 for chrominance components.
344 */
345
346 cinfo->jpeg_color_space = colorspace;
347
348 cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */
349 cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */
350
351 switch (colorspace) {
352 case JCS_GRAYSCALE:
353 cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
354 cinfo->num_components = 1;
355 /* JFIF specifies component ID 1 */
356 SET_COMP(0, 1, 1, 1, 0, 0, 0);
357 break;
358 case JCS_RGB:
359 cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */
360 cinfo->num_components = 3;
361 SET_COMP(0, 0x52 /* 'R' */, 1, 1, 0, 0, 0);
362 SET_COMP(1, 0x47 /* 'G' */, 1, 1, 0, 0, 0);
363 SET_COMP(2, 0x42 /* 'B' */, 1, 1, 0, 0, 0);
364 break;
365 case JCS_YCbCr:
366 cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
367 cinfo->num_components = 3;
368 /* JFIF specifies component IDs 1,2,3 */
369 /* We default to 2x2 subsamples of chrominance */
370 SET_COMP(0, 1, 2, 2, 0, 0, 0);
371 SET_COMP(1, 2, 1, 1, 1, 1, 1);
372 SET_COMP(2, 3, 1, 1, 1, 1, 1);
373 break;
374 case JCS_CMYK:
375 cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */
376 cinfo->num_components = 4;
377 SET_COMP(0, 0x43 /* 'C' */, 1, 1, 0, 0, 0);
378 SET_COMP(1, 0x4D /* 'M' */, 1, 1, 0, 0, 0);
379 SET_COMP(2, 0x59 /* 'Y' */, 1, 1, 0, 0, 0);
380 SET_COMP(3, 0x4B /* 'K' */, 1, 1, 0, 0, 0);
381 break;
382 case JCS_YCCK:
383 cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */
384 cinfo->num_components = 4;
385 SET_COMP(0, 1, 2, 2, 0, 0, 0);
386 SET_COMP(1, 2, 1, 1, 1, 1, 1);
387 SET_COMP(2, 3, 1, 1, 1, 1, 1);
388 SET_COMP(3, 4, 2, 2, 0, 0, 0);
389 break;
390 case JCS_UNKNOWN:
391 cinfo->num_components = cinfo->input_components;
392 if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS)
393 ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
394 MAX_COMPONENTS);
395 for (ci = 0; ci < cinfo->num_components; ci++) {
396 SET_COMP(ci, ci, 1, 1, 0, 0, 0);
397 }
398 break;
399 default:
400 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
401 }
402}
403
404
405#ifdef C_PROGRESSIVE_SUPPORTED
406
407LOCAL(jpeg_scan_info *)
408fill_a_scan(jpeg_scan_info *scanptr, int ci, int Ss, int Se, int Ah, int Al)
409/* Support routine: generate one scan for specified component */
410{
411 scanptr->comps_in_scan = 1;
412 scanptr->component_index[0] = ci;
413 scanptr->Ss = Ss;
414 scanptr->Se = Se;
415 scanptr->Ah = Ah;
416 scanptr->Al = Al;
417 scanptr++;
418 return scanptr;
419}
420
421LOCAL(jpeg_scan_info *)
422fill_scans(jpeg_scan_info *scanptr, int ncomps, int Ss, int Se, int Ah, int Al)
423/* Support routine: generate one scan for each component */
424{
425 int ci;
426
427 for (ci = 0; ci < ncomps; ci++) {
428 scanptr->comps_in_scan = 1;
429 scanptr->component_index[0] = ci;
430 scanptr->Ss = Ss;
431 scanptr->Se = Se;
432 scanptr->Ah = Ah;
433 scanptr->Al = Al;
434 scanptr++;
435 }
436 return scanptr;
437}
438
439LOCAL(jpeg_scan_info *)
440fill_dc_scans(jpeg_scan_info *scanptr, int ncomps, int Ah, int Al)
441/* Support routine: generate interleaved DC scan if possible, else N scans */
442{
443 int ci;
444
445 if (ncomps <= MAX_COMPS_IN_SCAN) {
446 /* Single interleaved DC scan */
447 scanptr->comps_in_scan = ncomps;
448 for (ci = 0; ci < ncomps; ci++)
449 scanptr->component_index[ci] = ci;
450 scanptr->Ss = scanptr->Se = 0;
451 scanptr->Ah = Ah;
452 scanptr->Al = Al;
453 scanptr++;
454 } else {
455 /* Noninterleaved DC scan for each component */
456 scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al);
457 }
458 return scanptr;
459}
460
461
462/*
463 * Create a recommended progressive-JPEG script.
464 * cinfo->num_components and cinfo->jpeg_color_space must be correct.
465 */
466
467GLOBAL(void)
468jpeg_simple_progression(j_compress_ptr cinfo)
469{
470 int ncomps = cinfo->num_components;
471 int nscans;
472 jpeg_scan_info *scanptr;
473
474 /* Safety check to ensure start_compress not called yet. */
475 if (cinfo->global_state != CSTATE_START)
476 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
477
478 /* Figure space needed for script. Calculation must match code below! */
479 if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
480 /* Custom script for YCbCr color images. */
481 nscans = 10;
482 } else {
483 /* All-purpose script for other color spaces. */
484 if (ncomps > MAX_COMPS_IN_SCAN)
485 nscans = 6 * ncomps; /* 2 DC + 4 AC scans per component */
486 else
487 nscans = 2 + 4 * ncomps; /* 2 DC scans; 4 AC scans per component */
488 }
489
490 /* Allocate space for script.
491 * We need to put it in the permanent pool in case the application performs
492 * multiple compressions without changing the settings. To avoid a memory
493 * leak if jpeg_simple_progression is called repeatedly for the same JPEG
494 * object, we try to re-use previously allocated space, and we allocate
495 * enough space to handle YCbCr even if initially asked for grayscale.
496 */
497 if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) {
498 cinfo->script_space_size = MAX(nscans, 10);
499 cinfo->script_space = (jpeg_scan_info *)
500 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_PERMANENT,
501 cinfo->script_space_size * sizeof(jpeg_scan_info));
502 }
503 scanptr = cinfo->script_space;
504 cinfo->scan_info = scanptr;
505 cinfo->num_scans = nscans;
506
507 if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
508 /* Custom script for YCbCr color images. */
509 /* Initial DC scan */
510 scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
511 /* Initial AC scan: get some luma data out in a hurry */
512 scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2);
513 /* Chroma data is too small to be worth expending many scans on */
514 scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1);
515 scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1);
516 /* Complete spectral selection for luma AC */
517 scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2);
518 /* Refine next bit of luma AC */
519 scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1);
520 /* Finish DC successive approximation */
521 scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
522 /* Finish AC successive approximation */
523 scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0);
524 scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0);
525 /* Luma bottom bit comes last since it's usually largest scan */
526 scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0);
527 } else {
528 /* All-purpose script for other color spaces. */
529 /* Successive approximation first pass */
530 scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
531 scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2);
532 scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2);
533 /* Successive approximation second pass */
534 scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1);
535 /* Successive approximation final pass */
536 scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
537 scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0);
538 }
539}
540
541#endif /* C_PROGRESSIVE_SUPPORTED */
542