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cjpeg option for baseline quant tables

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Add command line option -quant-baseline to cjpeg to force quantization
table entries to be in 1-255 range for JPEG baseline compatibility. See
related discussion in #145
This commit is contained in:
Frank Bossen
2015-03-23 14:05:13 -05:00
parent cc11b90b22
commit f8a5b80cb0
1 changed files with 7 additions and 2 deletions
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7
cjpeg.c
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@@ -207,6 +207,7 @@ usage (void)
fprintf(stderr, " -dct float Use floating-point DCT method%s\n", fprintf(stderr, " -dct float Use floating-point DCT method%s\n",
(JDCT_DEFAULT == JDCT_FLOAT ? " (default)" : "")); (JDCT_DEFAULT == JDCT_FLOAT ? " (default)" : ""));
#endif #endif
fprintf(stderr, " -quant-baseline Use 8-bit quantization table entries for baseline JPEG compatibility\n");
fprintf(stderr, " -quant-table N Use predefined quantization table N:\n"); fprintf(stderr, " -quant-table N Use predefined quantization table N:\n");
fprintf(stderr, " - 0 JPEG Annex K\n"); fprintf(stderr, " - 0 JPEG Annex K\n");
fprintf(stderr, " - 1 Flat\n"); fprintf(stderr, " - 1 Flat\n");
@@ -450,7 +451,7 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
qtablefile = argv[argn]; qtablefile = argv[argn];
/* We postpone actually reading the file in case -quality comes later. */ /* We postpone actually reading the file in case -quality comes later. */
} else if (keymatch(arg, "quant-table", 2)) { } else if (keymatch(arg, "quant-table", 7)) {
int val; int val;
if (++argn >= argc) /* advance to next argument */ if (++argn >= argc) /* advance to next argument */
usage(); usage();
@@ -462,6 +463,10 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
} }
jpeg_set_quality(cinfo, 75, TRUE); jpeg_set_quality(cinfo, 75, TRUE);
} else if (keymatch(arg, "quant-baseline", 7)) {
/* Force quantization table to meet baseline requirements */
force_baseline = TRUE;
} else if (keymatch(arg, "restart", 1)) { } else if (keymatch(arg, "restart", 1)) {
/* Restart interval in MCU rows (or in MCUs with 'b'). */ /* Restart interval in MCU rows (or in MCUs with 'b'). */
long lval; long lval;