ref: 2c6cc121339ade33ac5aa4b46356df1cd5469fbe
dir: /sys/src/cmd/gs/jpeg/rdcolmap.c/
/*
* rdcolmap.c
*
* Copyright (C) 1994-1996, 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 implements djpeg's "-map file" switch. It reads a source image
* and constructs a colormap to be supplied to the JPEG decompressor.
*
* Currently, these file formats are supported for the map file:
* GIF: the contents of the GIF's global colormap are used.
* PPM (either text or raw flavor): the entire file is read and
* each unique pixel value is entered in the map.
* Note that reading a large PPM file will be horrendously slow.
* Typically, a PPM-format map file should contain just one pixel
* of each desired color. Such a file can be extracted from an
* ordinary image PPM file with ppmtomap(1).
*
* Rescaling a PPM that has a maxval unequal to MAXJSAMPLE is not
* currently implemented.
*/
#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
#ifdef QUANT_2PASS_SUPPORTED /* otherwise can't quantize to supplied map */
/* Portions of this code are based on the PBMPLUS library, which is:
**
** Copyright (C) 1988 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
/*
* Add a (potentially) new color to the color map.
*/
LOCAL(void)
add_map_entry (j_decompress_ptr cinfo, int R, int G, int B)
{
JSAMPROW colormap0 = cinfo->colormap[0];
JSAMPROW colormap1 = cinfo->colormap[1];
JSAMPROW colormap2 = cinfo->colormap[2];
int ncolors = cinfo->actual_number_of_colors;
int index;
/* Check for duplicate color. */
for (index = 0; index < ncolors; index++) {
if (GETJSAMPLE(colormap0[index]) == R &&
GETJSAMPLE(colormap1[index]) == G &&
GETJSAMPLE(colormap2[index]) == B)
return; /* color is already in map */
}
/* Check for map overflow. */
if (ncolors >= (MAXJSAMPLE+1))
ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, (MAXJSAMPLE+1));
/* OK, add color to map. */
colormap0[ncolors] = (JSAMPLE) R;
colormap1[ncolors] = (JSAMPLE) G;
colormap2[ncolors] = (JSAMPLE) B;
cinfo->actual_number_of_colors++;
}
/*
* Extract color map from a GIF file.
*/
LOCAL(void)
read_gif_map (j_decompress_ptr cinfo, FILE * infile)
{
int header[13];
int i, colormaplen;
int R, G, B;
/* Initial 'G' has already been read by read_color_map */
/* Read the rest of the GIF header and logical screen descriptor */
for (i = 1; i < 13; i++) {
if ((header[i] = getc(infile)) == EOF)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
}
/* Verify GIF Header */
if (header[1] != 'I' || header[2] != 'F')
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
/* There must be a global color map. */
if ((header[10] & 0x80) == 0)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
/* OK, fetch it. */
colormaplen = 2 << (header[10] & 0x07);
for (i = 0; i < colormaplen; i++) {
R = getc(infile);
G = getc(infile);
B = getc(infile);
if (R == EOF || G == EOF || B == EOF)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
add_map_entry(cinfo,
R << (BITS_IN_JSAMPLE-8),
G << (BITS_IN_JSAMPLE-8),
B << (BITS_IN_JSAMPLE-8));
}
}
/* Support routines for reading PPM */
LOCAL(int)
pbm_getc (FILE * infile)
/* Read next char, skipping over any comments */
/* A comment/newline sequence is returned as a newline */
{
register int ch;
ch = getc(infile);
if (ch == '#') {
do {
ch = getc(infile);
} while (ch != '\n' && ch != EOF);
}
return ch;
}
LOCAL(unsigned int)
read_pbm_integer (j_decompress_ptr cinfo, FILE * infile)
/* Read an unsigned decimal integer from the PPM file */
/* Swallows one trailing character after the integer */
/* Note that on a 16-bit-int machine, only values up to 64k can be read. */
/* This should not be a problem in practice. */
{
register int ch;
register unsigned int val;
/* Skip any leading whitespace */
do {
ch = pbm_getc(infile);
if (ch == EOF)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
} while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
if (ch < '0' || ch > '9')
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
val = ch - '0';
while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') {
val *= 10;
val += ch - '0';
}
return val;
}
/*
* Extract color map from a PPM file.
*/
LOCAL(void)
read_ppm_map (j_decompress_ptr cinfo, FILE * infile)
{
int c;
unsigned int w, h, maxval, row, col;
int R, G, B;
/* Initial 'P' has already been read by read_color_map */
c = getc(infile); /* save format discriminator for a sec */
/* while we fetch the remaining header info */
w = read_pbm_integer(cinfo, infile);
h = read_pbm_integer(cinfo, infile);
maxval = read_pbm_integer(cinfo, infile);
if (w <= 0 || h <= 0 || maxval <= 0) /* error check */
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
/* For now, we don't support rescaling from an unusual maxval. */
if (maxval != (unsigned int) MAXJSAMPLE)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
switch (c) {
case '3': /* it's a text-format PPM file */
for (row = 0; row < h; row++) {
for (col = 0; col < w; col++) {
R = read_pbm_integer(cinfo, infile);
G = read_pbm_integer(cinfo, infile);
B = read_pbm_integer(cinfo, infile);
add_map_entry(cinfo, R, G, B);
}
}
break;
case '6': /* it's a raw-format PPM file */
for (row = 0; row < h; row++) {
for (col = 0; col < w; col++) {
R = getc(infile);
G = getc(infile);
B = getc(infile);
if (R == EOF || G == EOF || B == EOF)
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
add_map_entry(cinfo, R, G, B);
}
}
break;
default:
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
break;
}
}
/*
* Main entry point from djpeg.c.
* Input: opened input file (from file name argument on command line).
* Output: colormap and actual_number_of_colors fields are set in cinfo.
*/
GLOBAL(void)
read_color_map (j_decompress_ptr cinfo, FILE * infile)
{
/* Allocate space for a color map of maximum supported size. */
cinfo->colormap = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
(JDIMENSION) (MAXJSAMPLE+1), (JDIMENSION) 3);
cinfo->actual_number_of_colors = 0; /* initialize map to empty */
/* Read first byte to determine file format */
switch (getc(infile)) {
case 'G':
read_gif_map(cinfo, infile);
break;
case 'P':
read_ppm_map(cinfo, infile);
break;
default:
ERREXIT(cinfo, JERR_BAD_CMAP_FILE);
break;
}
}
#endif /* QUANT_2PASS_SUPPORTED */