diff options
Diffstat (limited to 'jpg/rdcolmap.c')
| -rw-r--r-- | jpg/rdcolmap.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/jpg/rdcolmap.c b/jpg/rdcolmap.c new file mode 100644 index 0000000..42b3437 --- /dev/null +++ b/jpg/rdcolmap.c @@ -0,0 +1,253 @@ +/* + * 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 */ |