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
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.
17 #define JPEG_INTERNALS
24 * Quantization table setup routines
28 jpeg_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.
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
);
45 if (which_tbl
< 0 || which_tbl
>= NUM_QUANT_TBLS
)
46 ERREXIT1(cinfo
, JERR_DQT_INDEX
, which_tbl
);
48 qtblptr
= &cinfo
->quant_tbl_ptrs
[which_tbl
];
51 *qtblptr
= jpeg_alloc_quant_table((j_common_ptr
)cinfo
);
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
;
63 /* Initialize sent_table FALSE so table will be written to JPEG file. */
64 (*qtblptr
)->sent_table
= FALSE
;
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.
73 static 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
83 static 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
95 #if JPEG_LIB_VERSION >= 70
97 jpeg_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.
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
);
113 jpeg_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.
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
);
130 jpeg_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).
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;
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.
147 quality
= 5000 / quality
;
149 quality
= 200 - quality
* 2;
156 jpeg_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.
163 /* Convert user 0-100 rating to percentage scaling */
164 quality
= jpeg_quality_scaling(quality
);
166 /* Set up standard quality tables */
167 jpeg_set_linear_quality(cinfo
, quality
, force_baseline
);
172 * Default parameter setup for compression.
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).
182 jpeg_set_defaults(j_compress_ptr cinfo
)
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
);
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.
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
));
199 /* Initialize everything not dependent on the color space */
201 #if JPEG_LIB_VERSION >= 70
202 cinfo
->scale_num
= 1; /* 1:1 scaling */
203 cinfo
->scale_denom
= 1;
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
);
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;
218 /* Default is no multiple-scan output */
219 cinfo
->scan_info
= NULL
;
220 cinfo
->num_scans
= 0;
222 /* Expect normal source image, not raw downsampled data */
223 cinfo
->raw_data_in
= FALSE
;
225 /* Use Huffman coding, not arithmetic coding, by default */
226 cinfo
->arith_code
= FALSE
;
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.
235 if (cinfo
->data_precision
> 8)
236 cinfo
->optimize_coding
= TRUE
;
238 /* By default, use the simpler non-cosited sampling alignment */
239 cinfo
->CCIR601_sampling
= FALSE
;
241 #if JPEG_LIB_VERSION >= 70
242 /* By default, apply fancy downsampling */
243 cinfo
->do_fancy_downsampling
= TRUE
;
246 /* No input smoothing */
247 cinfo
->smoothing_factor
= 0;
249 /* DCT algorithm preference */
250 cinfo
->dct_method
= JDCT_DEFAULT
;
252 /* No restart markers */
253 cinfo
->restart_interval
= 0;
254 cinfo
->restart_in_rows
= 0;
256 /* Fill in default JFIF marker parameters. Note that whether the marker
257 * will actually be written is determined by jpeg_set_colorspace.
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.
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;
271 /* Choose JPEG colorspace based on input space, set defaults accordingly */
273 jpeg_default_colorspace(cinfo
);
278 * Select an appropriate JPEG colorspace for in_color_space.
282 jpeg_default_colorspace(j_compress_ptr cinfo
)
284 switch (cinfo
->in_color_space
) {
286 jpeg_set_colorspace(cinfo
, JCS_GRAYSCALE
);
299 jpeg_set_colorspace(cinfo
, JCS_YCbCr
);
302 jpeg_set_colorspace(cinfo
, JCS_YCbCr
);
305 jpeg_set_colorspace(cinfo
, JCS_CMYK
); /* By default, no translation */
308 jpeg_set_colorspace(cinfo
, JCS_YCCK
);
311 jpeg_set_colorspace(cinfo
, JCS_UNKNOWN
);
314 ERREXIT(cinfo
, JERR_BAD_IN_COLORSPACE
);
320 * Set the JPEG colorspace, and choose colorspace-dependent default values.
324 jpeg_set_colorspace(j_compress_ptr cinfo
, J_COLOR_SPACE colorspace
)
326 jpeg_component_info
*compptr
;
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) )
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
);
342 /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
343 * tables 1 for chrominance components.
346 cinfo
->jpeg_color_space
= colorspace
;
348 cinfo
->write_JFIF_header
= FALSE
; /* No marker for non-JFIF colorspaces */
349 cinfo
->write_Adobe_marker
= FALSE
; /* write no Adobe marker by default */
351 switch (colorspace
) {
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);
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);
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);
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);
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);
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
,
395 for (ci
= 0; ci
< cinfo
->num_components
; ci
++) {
396 SET_COMP(ci
, ci
, 1, 1, 0, 0, 0);
400 ERREXIT(cinfo
, JERR_BAD_J_COLORSPACE
);
405 #ifdef C_PROGRESSIVE_SUPPORTED
407 LOCAL(jpeg_scan_info
*)
408 fill_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 */
411 scanptr
->comps_in_scan
= 1;
412 scanptr
->component_index
[0] = ci
;
421 LOCAL(jpeg_scan_info
*)
422 fill_scans(jpeg_scan_info
*scanptr
, int ncomps
, int Ss
, int Se
, int Ah
, int Al
)
423 /* Support routine: generate one scan for each component */
427 for (ci
= 0; ci
< ncomps
; ci
++) {
428 scanptr
->comps_in_scan
= 1;
429 scanptr
->component_index
[0] = ci
;
439 LOCAL(jpeg_scan_info
*)
440 fill_dc_scans(jpeg_scan_info
*scanptr
, int ncomps
, int Ah
, int Al
)
441 /* Support routine: generate interleaved DC scan if possible, else N scans */
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;
455 /* Noninterleaved DC scan for each component */
456 scanptr
= fill_scans(scanptr
, ncomps
, 0, 0, Ah
, Al
);
463 * Create a recommended progressive-JPEG script.
464 * cinfo->num_components and cinfo->jpeg_color_space must be correct.
468 jpeg_simple_progression(j_compress_ptr cinfo
)
470 int ncomps
= cinfo
->num_components
;
472 jpeg_scan_info
*scanptr
;
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
);
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. */
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 */
487 nscans
= 2 + 4 * ncomps
; /* 2 DC scans; 4 AC scans per component */
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.
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
));
503 scanptr
= cinfo
->script_space
;
504 cinfo
->scan_info
= scanptr
;
505 cinfo
->num_scans
= nscans
;
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);
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);
541 #endif /* C_PROGRESSIVE_SUPPORTED */