JPEG-量化表源码
jpeg_add_quant_table()
libjpeg-turbo/jcparam.c
https://github.com/libjpeg-turbo/libjpeg-turbo/blob/main/jcparam.c#L30
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;
}
libjpeg
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;
}
cjpeg.c
/*
* cjpeg.c
*
* Copyright (C) 1991-1998, Thomas G. Lane.
* Modified 2003-2010 by Guido Vollbeding.
* 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 a command-line user interface for the JPEG compressor.
* It should work on any system with Unix- or MS-DOS-style command lines.
*
* Two different command line styles are permitted, depending on the
* compile-time switch TWO_FILE_COMMANDLINE:
* cjpeg [options] inputfile outputfile
* cjpeg [options] [inputfile]
* In the second style, output is always to standard output, which you'd
* normally redirect to a file or pipe to some other program. Input is
* either from a named file or from standard input (typically redirected).
* The second style is convenient on Unix but is unhelpful on systems that
* don't support pipes. Also, you MUST use the first style if your system
* doesn't do binary I/O to stdin/stdout.
* To simplify script writing, the "-outfile" switch is provided. The syntax
* cjpeg [options] -outfile outputfile inputfile
* works regardless of which command line style is used.
*/
#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
#include "jversion.h" /* for version message */
#ifdef USE_CCOMMAND /* command-line reader for Macintosh */
#ifdef __MWERKS__
#include <SIOUX.h> /* Metrowerks needs this */
#include <console.h> /* ... and this */
#endif
#ifdef THINK_C
#include <console.h> /* Think declares it here */
#endif
#endif
/* Create the add-on message string table. */
#define JMESSAGE(code,string) string ,
static const char * const cdjpeg_message_table[] = {
#include "cderror.h"
NULL
};
/*
* This routine determines what format the input file is,
* and selects the appropriate input-reading module.
*
* To determine which family of input formats the file belongs to,
* we may look only at the first byte of the file, since C does not
* guarantee that more than one character can be pushed back with ungetc.
* Looking at additional bytes would require one of these approaches:
* 1) assume we can fseek() the input file (fails for piped input);
* 2) assume we can push back more than one character (works in
* some C implementations, but unportable);
* 3) provide our own buffering (breaks input readers that want to use
* stdio directly, such as the RLE library);
* or 4) don't put back the data, and modify the input_init methods to assume
* they start reading after the start of file (also breaks RLE library).
* #1 is attractive for MS-DOS but is untenable on Unix.
*
* The most portable solution for file types that can't be identified by their
* first byte is to make the user tell us what they are. This is also the
* only approach for "raw" file types that contain only arbitrary values.
* We presently apply this method for Targa files. Most of the time Targa
* files start with 0x00, so we recognize that case. Potentially, however,
* a Targa file could start with any byte value (byte 0 is the length of the
* seldom-used ID field), so we provide a switch to force Targa input mode.
*/
static boolean is_targa; /* records user -targa switch */
LOCAL(cjpeg_source_ptr)
select_file_type (j_compress_ptr cinfo, FILE * infile)
{
int c;
if (is_targa) {
#ifdef TARGA_SUPPORTED
return jinit_read_targa(cinfo);
#else
ERREXIT(cinfo, JERR_TGA_NOTCOMP);
#endif
}
if ((c = getc(infile)) == EOF)
ERREXIT(cinfo, JERR_INPUT_EMPTY);
if (ungetc(c, infile) == EOF)
ERREXIT(cinfo, JERR_UNGETC_FAILED);
switch (c) {
#ifdef BMP_SUPPORTED
case 'B':
return jinit_read_bmp(cinfo);
#endif
#ifdef GIF_SUPPORTED
case 'G':
return jinit_read_gif(cinfo);
#endif
#ifdef PPM_SUPPORTED
case 'P':
return jinit_read_ppm(cinfo);
#endif
#ifdef RLE_SUPPORTED
case 'R':
return jinit_read_rle(cinfo);
#endif
#ifdef TARGA_SUPPORTED
case 0x00:
return jinit_read_targa(cinfo);
#endif
default:
ERREXIT(cinfo, JERR_UNKNOWN_FORMAT);
break;
}
return NULL; /* suppress compiler warnings */
}
/*
* Argument-parsing code.
* The switch parser is designed to be useful with DOS-style command line
* syntax, ie, intermixed switches and file names, where only the switches
* to the left of a given file name affect processing of that file.
* The main program in this file doesn't actually use this capability...
*/
static const char * progname; /* program name for error messages */
static char * outfilename; /* for -outfile switch */
LOCAL(void)
usage (void)
/* complain about bad command line */
{
fprintf(stderr, "usage: %s [switches] ", progname);
#ifdef TWO_FILE_COMMANDLINE
fprintf(stderr, "inputfile outputfile\n");
#else
fprintf(stderr, "[inputfile]\n");
#endif
fprintf(stderr, "Switches (names may be abbreviated):\n");
fprintf(stderr, " -quality N[,...] Compression quality (0..100; 5-95 is useful range)\n");
fprintf(stderr, " -grayscale Create monochrome JPEG file\n");
#ifdef ENTROPY_OPT_SUPPORTED
fprintf(stderr, " -optimize Optimize Huffman table (smaller file, but slow compression)\n");
#endif
#ifdef C_PROGRESSIVE_SUPPORTED
fprintf(stderr, " -progressive Create progressive JPEG file\n");
#endif
#ifdef DCT_SCALING_SUPPORTED
fprintf(stderr, " -scale M/N Scale image by fraction M/N, eg, 1/2\n");
#endif
#ifdef TARGA_SUPPORTED
fprintf(stderr, " -targa Input file is Targa format (usually not needed)\n");
#endif
fprintf(stderr, "Switches for advanced users:\n");
#ifdef DCT_SCALING_SUPPORTED
fprintf(stderr, " -block N DCT block size (1..16; default is 8)\n");
#endif
#ifdef DCT_ISLOW_SUPPORTED
fprintf(stderr, " -dct int Use integer DCT method%s\n",
(JDCT_DEFAULT == JDCT_ISLOW ? " (default)" : ""));
#endif
#ifdef DCT_IFAST_SUPPORTED
fprintf(stderr, " -dct fast Use fast integer DCT (less accurate)%s\n",
(JDCT_DEFAULT == JDCT_IFAST ? " (default)" : ""));
#endif
#ifdef DCT_FLOAT_SUPPORTED
fprintf(stderr, " -dct float Use floating-point DCT method%s\n",
(JDCT_DEFAULT == JDCT_FLOAT ? " (default)" : ""));
#endif
fprintf(stderr, " -nosmooth Don't use high-quality downsampling\n");
fprintf(stderr, " -restart N Set restart interval in rows, or in blocks with B\n");
#ifdef INPUT_SMOOTHING_SUPPORTED
fprintf(stderr, " -smooth N Smooth dithered input (N=1..100 is strength)\n");
#endif
fprintf(stderr, " -maxmemory N Maximum memory to use (in kbytes)\n");
fprintf(stderr, " -outfile name Specify name for output file\n");
fprintf(stderr, " -verbose or -debug Emit debug output\n");
fprintf(stderr, "Switches for wizards:\n");
#ifdef C_ARITH_CODING_SUPPORTED
fprintf(stderr, " -arithmetic Use arithmetic coding\n");
#endif
fprintf(stderr, " -baseline Force baseline quantization tables\n");
fprintf(stderr, " -qtables file Use quantization tables given in file\n");
fprintf(stderr, " -qslots N[,...] Set component quantization tables\n");
fprintf(stderr, " -sample HxV[,...] Set component sampling factors\n");
#ifdef C_MULTISCAN_FILES_SUPPORTED
fprintf(stderr, " -scans file Create multi-scan JPEG per script file\n");
#endif
exit(EXIT_FAILURE);
}
LOCAL(int)
parse_switches (j_compress_ptr cinfo, int argc, char **argv,
int last_file_arg_seen, boolean for_real)
/* Parse optional switches.
* Returns argv[] index of first file-name argument (== argc if none).
* Any file names with indexes <= last_file_arg_seen are ignored;
* they have presumably been processed in a previous iteration.
* (Pass 0 for last_file_arg_seen on the first or only iteration.)
* for_real is FALSE on the first (dummy) pass; we may skip any expensive
* processing.
*/
{
int argn;
char * arg;
boolean force_baseline;
boolean simple_progressive;
char * qualityarg = NULL; /* saves -quality parm if any */
char * qtablefile = NULL; /* saves -qtables filename if any */
char * qslotsarg = NULL; /* saves -qslots parm if any */
char * samplearg = NULL; /* saves -sample parm if any */
char * scansarg = NULL; /* saves -scans parm if any */
/* Set up default JPEG parameters. */
force_baseline = FALSE; /* by default, allow 16-bit quantizers */
simple_progressive = FALSE;
is_targa = FALSE;
outfilename = NULL;
cinfo->err->trace_level = 0;
/* Scan command line options, adjust parameters */
for (argn = 1; argn < argc; argn++) {
arg = argv[argn];
if (*arg != '-') {
/* Not a switch, must be a file name argument */
if (argn <= last_file_arg_seen) {
outfilename = NULL; /* -outfile applies to just one input file */
continue; /* ignore this name if previously processed */
}
break; /* else done parsing switches */
}
arg++; /* advance past switch marker character */
if (keymatch(arg, "arithmetic", 1)) {
/* Use arithmetic coding. */
#ifdef C_ARITH_CODING_SUPPORTED
cinfo->arith_code = TRUE;
#else
fprintf(stderr, "%s: sorry, arithmetic coding not supported\n",
progname);
exit(EXIT_FAILURE);
#endif
} else if (keymatch(arg, "baseline", 2)) {
/* Force baseline-compatible output (8-bit quantizer values). */
force_baseline = TRUE;
} else if (keymatch(arg, "block", 2)) {
/* Set DCT block size. */
#if defined(DCT_SCALING_SUPPORTED) && defined(JPEG_LIB_VERSION_MAJOR) && \
(JPEG_LIB_VERSION_MAJOR > 8 || (JPEG_LIB_VERSION_MAJOR == 8 && \
defined(JPEG_LIB_VERSION_MINOR) && JPEG_LIB_VERSION_MINOR >= 3))
int val;
if (++argn >= argc) /* advance to next argument */
usage();
if (sscanf(argv[argn], "%d", &val) != 1)
usage();
if (val < 1 || val > 16)
usage();
cinfo->block_size = val;
#else
fprintf(stderr, "%s: sorry, block size setting not supported\n",
progname);
exit(EXIT_FAILURE);
#endif
} else if (keymatch(arg, "dct", 2)) {
/* Select DCT algorithm. */
if (++argn >= argc) /* advance to next argument */
usage();
if (keymatch(argv[argn], "int", 1)) {
cinfo->dct_method = JDCT_ISLOW;
} else if (keymatch(argv[argn], "fast", 2)) {
cinfo->dct_method = JDCT_IFAST;
} else if (keymatch(argv[argn], "float", 2)) {
cinfo->dct_method = JDCT_FLOAT;
} else
usage();
} else if (keymatch(arg, "debug", 1) || keymatch(arg, "verbose", 1)) {
/* Enable debug printouts. */
/* On first -d, print version identification */
static boolean printed_version = FALSE;
if (! printed_version) {
fprintf(stderr, "Independent JPEG Group's CJPEG, version %s\n%s\n",
JVERSION, JCOPYRIGHT);
printed_version = TRUE;
}
cinfo->err->trace_level++;
} else if (keymatch(arg, "grayscale", 2) || keymatch(arg, "greyscale",2)) {
/* Force a monochrome JPEG file to be generated. */
jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
} else if (keymatch(arg, "maxmemory", 3)) {
/* Maximum memory in Kb (or Mb with 'm'). */
long lval;
char ch = 'x';
if (++argn >= argc) /* advance to next argument */
usage();
if (sscanf(argv[argn], "%ld%c", &lval, &ch) < 1)
usage();
if (ch == 'm' || ch == 'M')
lval *= 1000L;
cinfo->mem->max_memory_to_use = lval * 1000L;
} else if (keymatch(arg, "nosmooth", 3)) {
/* Suppress fancy downsampling */
cinfo->do_fancy_downsampling = FALSE;
} else if (keymatch(arg, "optimize", 1) || keymatch(arg, "optimise", 1)) {
/* Enable entropy parm optimization. */
#ifdef ENTROPY_OPT_SUPPORTED
cinfo->optimize_coding = TRUE;
#else
fprintf(stderr, "%s: sorry, entropy optimization was not compiled\n",
progname);
exit(EXIT_FAILURE);
#endif
} else if (keymatch(arg, "outfile", 4)) {
/* Set output file name. */
if (++argn >= argc) /* advance to next argument */
usage();
outfilename = argv[argn]; /* save it away for later use */
} else if (keymatch(arg, "progressive", 1)) {
/* Select simple progressive mode. */
#ifdef C_PROGRESSIVE_SUPPORTED
simple_progressive = TRUE;
/* We must postpone execution until num_components is known. */
#else
fprintf(stderr, "%s: sorry, progressive output was not compiled\n",
progname);
exit(EXIT_FAILURE);
#endif
} else if (keymatch(arg, "quality", 1)) {
/* Quality ratings (quantization table scaling factors). */
if (++argn >= argc) /* advance to next argument */
usage();
qualityarg = argv[argn];
} else if (keymatch(arg, "qslots", 2)) {
/* Quantization table slot numbers. */
if (++argn >= argc) /* advance to next argument */
usage();
qslotsarg = argv[argn];
/* Must delay setting qslots until after we have processed any
* colorspace-determining switches, since jpeg_set_colorspace sets
* default quant table numbers.
*/
} else if (keymatch(arg, "qtables", 2)) {
/* Quantization tables fetched from file. */
if (++argn >= argc) /* advance to next argument */
usage();
qtablefile = argv[argn];
/* We postpone actually reading the file in case -quality comes later. */
} else if (keymatch(arg, "restart", 1)) {
/* Restart interval in MCU rows (or in MCUs with 'b'). */
long lval;
char ch = 'x';
if (++argn >= argc) /* advance to next argument */
usage();
if (sscanf(argv[argn], "%ld%c", &lval, &ch) < 1)
usage();
if (lval < 0 || lval > 65535L)
usage();
if (ch == 'b' || ch == 'B') {
cinfo->restart_interval = (unsigned int) lval;
cinfo->restart_in_rows = 0; /* else prior '-restart n' overrides me */
} else {
cinfo->restart_in_rows = (int) lval;
/* restart_interval will be computed during startup */
}
} else if (keymatch(arg, "sample", 2)) {
/* Set sampling factors. */
if (++argn >= argc) /* advance to next argument */
usage();
samplearg = argv[argn];
/* Must delay setting sample factors until after we have processed any
* colorspace-determining switches, since jpeg_set_colorspace sets
* default sampling factors.
*/
} else if (keymatch(arg, "scale", 4)) {
/* Scale the image by a fraction M/N. */
if (++argn >= argc) /* advance to next argument */
usage();
if (sscanf(argv[argn], "%d/%d",
&cinfo->scale_num, &cinfo->scale_denom) != 2)
usage();
} else if (keymatch(arg, "scans", 4)) {
/* Set scan script. */
#ifdef C_MULTISCAN_FILES_SUPPORTED
if (++argn >= argc) /* advance to next argument */
usage();
scansarg = argv[argn];
/* We must postpone reading the file in case -progressive appears. */
#else
fprintf(stderr, "%s: sorry, multi-scan output was not compiled\n",
progname);
exit(EXIT_FAILURE);
#endif
} else if (keymatch(arg, "smooth", 2)) {
/* Set input smoothing factor. */
int val;
if (++argn >= argc) /* advance to next argument */
usage();
if (sscanf(argv[argn], "%d", &val) != 1)
usage();
if (val < 0 || val > 100)
usage();
cinfo->smoothing_factor = val;
} else if (keymatch(arg, "targa", 1)) {
/* Input file is Targa format. */
is_targa = TRUE;
} else {
usage(); /* bogus switch */
}
}
/* Post-switch-scanning cleanup */
if (for_real) {
/* Set quantization tables for selected quality. */
/* Some or all may be overridden if -qtables is present. */
if (qualityarg != NULL) /* process -quality if it was present */
if (! set_quality_ratings(cinfo, qualityarg, force_baseline))
usage();
if (qtablefile != NULL) /* process -qtables if it was present */
if (! read_quant_tables(cinfo, qtablefile, force_baseline))
usage();
if (qslotsarg != NULL) /* process -qslots if it was present */
if (! set_quant_slots(cinfo, qslotsarg))
usage();
if (samplearg != NULL) /* process -sample if it was present */
if (! set_sample_factors(cinfo, samplearg))
usage();
#ifdef C_PROGRESSIVE_SUPPORTED
if (simple_progressive) /* process -progressive; -scans can override */
jpeg_simple_progression(cinfo);
#endif
#ifdef C_MULTISCAN_FILES_SUPPORTED
if (scansarg != NULL) /* process -scans if it was present */
if (! read_scan_script(cinfo, scansarg))
usage();
#endif
}
return argn; /* return index of next arg (file name) */
}
/*
* The main program.
*/
int
main (int argc, char **argv)
{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
#ifdef PROGRESS_REPORT
struct cdjpeg_progress_mgr progress;
#endif
int file_index;
cjpeg_source_ptr src_mgr;
FILE * input_file;
FILE * output_file;
JDIMENSION num_scanlines;
/* On Mac, fetch a command line. */
#ifdef USE_CCOMMAND
argc = ccommand(&argv);
#endif
progname = argv[0];
if (progname == NULL || progname[0] == 0)
progname = "cjpeg"; /* in case C library doesn't provide it */
/* Initialize the JPEG compression object with default error handling. */
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
/* Add some application-specific error messages (from cderror.h) */
jerr.addon_message_table = cdjpeg_message_table;
jerr.first_addon_message = JMSG_FIRSTADDONCODE;
jerr.last_addon_message = JMSG_LASTADDONCODE;
/* Now safe to enable signal catcher. */
#ifdef NEED_SIGNAL_CATCHER
enable_signal_catcher((j_common_ptr) &cinfo);
#endif
/* Initialize JPEG parameters.
* Much of this may be overridden later.
* In particular, we don't yet know the input file's color space,
* but we need to provide some value for jpeg_set_defaults() to work.
*/
cinfo.in_color_space = JCS_RGB; /* arbitrary guess */
jpeg_set_defaults(&cinfo);
/* Scan command line to find file names.
* It is convenient to use just one switch-parsing routine, but the switch
* values read here are ignored; we will rescan the switches after opening
* the input file.
*/
file_index = parse_switches(&cinfo, argc, argv, 0, FALSE);
#ifdef TWO_FILE_COMMANDLINE
/* Must have either -outfile switch or explicit output file name */
if (outfilename == NULL) {
if (file_index != argc-2) {
fprintf(stderr, "%s: must name one input and one output file\n",
progname);
usage();
}
outfilename = argv[file_index+1];
} else {
if (file_index != argc-1) {
fprintf(stderr, "%s: must name one input and one output file\n",
progname);
usage();
}
}
#else
/* Unix style: expect zero or one file name */
if (file_index < argc-1) {
fprintf(stderr, "%s: only one input file\n", progname);
usage();
}
#endif /* TWO_FILE_COMMANDLINE */
/* Open the input file. */
if (file_index < argc) {
if ((input_file = fopen(argv[file_index], READ_BINARY)) == NULL) {
fprintf(stderr, "%s: can't open %s\n", progname, argv[file_index]);
exit(EXIT_FAILURE);
}
} else {
/* default input file is stdin */
input_file = read_stdin();
}
/* Open the output file. */
if (outfilename != NULL) {
if ((output_file = fopen(outfilename, WRITE_BINARY)) == NULL) {
fprintf(stderr, "%s: can't open %s\n", progname, outfilename);
exit(EXIT_FAILURE);
}
} else {
/* default output file is stdout */
output_file = write_stdout();
}
#ifdef PROGRESS_REPORT
start_progress_monitor((j_common_ptr) &cinfo, &progress);
#endif
/* Figure out the input file format, and set up to read it. */
src_mgr = select_file_type(&cinfo, input_file);
src_mgr->input_file = input_file;
/* Read the input file header to obtain file size & colorspace. */
(*src_mgr->start_input) (&cinfo, src_mgr);
/* Now that we know input colorspace, fix colorspace-dependent defaults */
jpeg_default_colorspace(&cinfo);
/* Adjust default compression parameters by re-parsing the options */
file_index = parse_switches(&cinfo, argc, argv, 0, TRUE);
/* Specify data destination for compression */
jpeg_stdio_dest(&cinfo, output_file);
/* Start compressor */
jpeg_start_compress(&cinfo, TRUE);
/* Process data */
while (cinfo.next_scanline < cinfo.image_height) {
num_scanlines = (*src_mgr->get_pixel_rows) (&cinfo, src_mgr);
(void) jpeg_write_scanlines(&cinfo, src_mgr->buffer, num_scanlines);
}
/* Finish compression and release memory */
(*src_mgr->finish_input) (&cinfo, src_mgr);
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
/* Close files, if we opened them */
if (input_file != stdin)
fclose(input_file);
if (output_file != stdout)
fclose(output_file);
#ifdef PROGRESS_REPORT
end_progress_monitor((j_common_ptr) &cinfo);
#endif
/* All done. */
exit(jerr.num_warnings ? EXIT_WARNING : EXIT_SUCCESS);
return 0; /* suppress no-return-value warnings */
}
jcparam.c
/*
* jcparam.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1991-1998, Thomas G. Lane.
* Modified 2003-2008 by Guido Vollbeding.
* Lossless JPEG Modifications:
* Copyright (C) 1999, Ken Murchison.
* libjpeg-turbo Modifications:
* Copyright (C) 2009-2011, 2018, 2023, D. R. Commander.
* For conditions of distribution and use, see the accompanying README.ijg
* 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"
#include "jstdhuff.c"
/*
* 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;
}
/* These are the sample quantization tables given in Annex K (Clause K.1) of
* Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
* 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
};
#if JPEG_LIB_VERSION >= 70
GLOBAL(void)
jpeg_default_qtables(j_compress_ptr cinfo, boolean force_baseline)
/* Set or change the 'quality' (quantization) setting, using default tables
* and straight percentage-scaling quality scales.
* This entry point allows different scalings for luminance and chrominance.
*/
{
/* Set up two quantization tables using the specified scaling */
jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
cinfo->q_scale_factor[0], force_baseline);
jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
cinfo->q_scale_factor[1], force_baseline);
}
#endif
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.
*/
{
/* 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);
}
/*
* 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 */
#if JPEG_LIB_VERSION >= 70
cinfo->scale_num = 1; /* 1:1 scaling */
cinfo->scale_denom = 1;
#endif
/* Set up two quantization tables using default quality of 75 */
jpeg_set_quality(cinfo, 75, TRUE);
/* Set up two Huffman tables */
std_huff_tables((j_common_ptr)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 == 12 && !cinfo->arith_code)
cinfo->optimize_coding = TRUE;
/* By default, use the simpler non-cosited sampling alignment */
cinfo->CCIR601_sampling = FALSE;
#if JPEG_LIB_VERSION >= 70
/* By default, apply fancy downsampling */
cinfo->do_fancy_downsampling = TRUE;
#endif
/* 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:
case JCS_EXT_RGB:
case JCS_EXT_RGBX:
case JCS_EXT_BGR:
case JCS_EXT_BGRX:
case JCS_EXT_XBGR:
case JCS_EXT_XRGB:
case JCS_EXT_RGBA:
case JCS_EXT_BGRA:
case JCS_EXT_ABGR:
case JCS_EXT_ARGB:
if (cinfo->master->lossless)
jpeg_set_colorspace(cinfo, JCS_RGB);
else
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);
if (cinfo->master->lossless) {
cinfo->master->lossless = FALSE;
jpeg_default_colorspace(cinfo);
}
/* 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 */
#ifdef C_LOSSLESS_SUPPORTED
/*
* Enable lossless mode.
*/
GLOBAL(void)
jpeg_enable_lossless(j_compress_ptr cinfo, int predictor_selection_value,
int point_transform)
{
/* Safety check to ensure start_compress not called yet. */
if (cinfo->global_state != CSTATE_START)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
cinfo->master->lossless = TRUE;
cinfo->Ss = predictor_selection_value;
cinfo->Se = 0;
cinfo->Ah = 0;
cinfo->Al = point_transform;
/* The JPEG spec simply gives the range 0..15 for Al (Pt), but that seems
* wrong: the upper bound ought to depend on data precision. Perhaps they
* really meant 0..N-1 for N-bit precision, which is what we allow here.
* Values greater than or equal to the data precision will result in a blank
* image.
*/
if (cinfo->Ss < 1 || cinfo->Ss > 7 ||
cinfo->Al < 0 || cinfo->Al >= cinfo->data_precision)
ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
}
#endif /* C_LOSSLESS_SUPPORTED */
