1 /* 2 * rdcolmap.c 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README.ijg 7 * file. 8 * 9 * This file implements djpeg's "-map file" switch. It reads a source image 10 * and constructs a colormap to be supplied to the JPEG decompressor. 11 * 12 * Currently, these file formats are supported for the map file: 13 * GIF: the contents of the GIF's global colormap are used. 14 * PPM (either text or raw flavor): the entire file is read and 15 * each unique pixel value is entered in the map. 16 * Note that reading a large PPM file will be horrendously slow. 17 * Typically, a PPM-format map file should contain just one pixel 18 * of each desired color. Such a file can be extracted from an 19 * ordinary image PPM file with ppmtomap(1). 20 * 21 * Rescaling a PPM that has a maxval unequal to MAXJSAMPLE is not 22 * currently implemented. 23 */ 24 25 #include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */ 26 27 #ifdef QUANT_2PASS_SUPPORTED /* otherwise can't quantize to supplied map */ 28 29 /* Portions of this code are based on the PBMPLUS library, which is: 30 ** 31 ** Copyright (C) 1988 by Jef Poskanzer. 32 ** 33 ** Permission to use, copy, modify, and distribute this software and its 34 ** documentation for any purpose and without fee is hereby granted, provided 35 ** that the above copyright notice appear in all copies and that both that 36 ** copyright notice and this permission notice appear in supporting 37 ** documentation. This software is provided "as is" without express or 38 ** implied warranty. 39 */ 40 41 42 /* 43 * Add a (potentially) new color to the color map. 44 */ 45 46 LOCAL(void) 47 add_map_entry (j_decompress_ptr cinfo, int R, int G, int B) 48 { 49 JSAMPROW colormap0 = cinfo->colormap[0]; 50 JSAMPROW colormap1 = cinfo->colormap[1]; 51 JSAMPROW colormap2 = cinfo->colormap[2]; 52 int ncolors = cinfo->actual_number_of_colors; 53 int index; 54 55 /* Check for duplicate color. */ 56 for (index = 0; index < ncolors; index++) { 57 if (GETJSAMPLE(colormap0[index]) == R && 58 GETJSAMPLE(colormap1[index]) == G && 59 GETJSAMPLE(colormap2[index]) == B) 60 return; /* color is already in map */ 61 } 62 63 /* Check for map overflow. */ 64 if (ncolors >= (MAXJSAMPLE+1)) 65 ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, (MAXJSAMPLE+1)); 66 67 /* OK, add color to map. */ 68 colormap0[ncolors] = (JSAMPLE) R; 69 colormap1[ncolors] = (JSAMPLE) G; 70 colormap2[ncolors] = (JSAMPLE) B; 71 cinfo->actual_number_of_colors++; 72 } 73 74 75 /* 76 * Extract color map from a GIF file. 77 */ 78 79 LOCAL(void) 80 read_gif_map (j_decompress_ptr cinfo, FILE *infile) 81 { 82 int header[13]; 83 int i, colormaplen; 84 int R, G, B; 85 86 /* Initial 'G' has already been read by read_color_map */ 87 /* Read the rest of the GIF header and logical screen descriptor */ 88 for (i = 1; i < 13; i++) { 89 if ((header[i] = getc(infile)) == EOF) 90 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 91 } 92 93 /* Verify GIF Header */ 94 if (header[1] != 'I' || header[2] != 'F') 95 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 96 97 /* There must be a global color map. */ 98 if ((header[10] & 0x80) == 0) 99 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 100 101 /* OK, fetch it. */ 102 colormaplen = 2 << (header[10] & 0x07); 103 104 for (i = 0; i < colormaplen; i++) { 105 R = getc(infile); 106 G = getc(infile); 107 B = getc(infile); 108 if (R == EOF || G == EOF || B == EOF) 109 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 110 add_map_entry(cinfo, 111 R << (BITS_IN_JSAMPLE-8), 112 G << (BITS_IN_JSAMPLE-8), 113 B << (BITS_IN_JSAMPLE-8)); 114 } 115 } 116 117 118 /* Support routines for reading PPM */ 119 120 121 LOCAL(int) 122 pbm_getc (FILE *infile) 123 /* Read next char, skipping over any comments */ 124 /* A comment/newline sequence is returned as a newline */ 125 { 126 register int ch; 127 128 ch = getc(infile); 129 if (ch == '#') { 130 do { 131 ch = getc(infile); 132 } while (ch != '\n' && ch != EOF); 133 } 134 return ch; 135 } 136 137 138 LOCAL(unsigned int) 139 read_pbm_integer (j_decompress_ptr cinfo, FILE *infile) 140 /* Read an unsigned decimal integer from the PPM file */ 141 /* Swallows one trailing character after the integer */ 142 /* Note that on a 16-bit-int machine, only values up to 64k can be read. */ 143 /* This should not be a problem in practice. */ 144 { 145 register int ch; 146 register unsigned int val; 147 148 /* Skip any leading whitespace */ 149 do { 150 ch = pbm_getc(infile); 151 if (ch == EOF) 152 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 153 } while (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r'); 154 155 if (ch < '0' || ch > '9') 156 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 157 158 val = ch - '0'; 159 while ((ch = pbm_getc(infile)) >= '0' && ch <= '9') { 160 val *= 10; 161 val += ch - '0'; 162 } 163 return val; 164 } 165 166 167 /* 168 * Extract color map from a PPM file. 169 */ 170 171 LOCAL(void) 172 read_ppm_map (j_decompress_ptr cinfo, FILE *infile) 173 { 174 int c; 175 unsigned int w, h, maxval, row, col; 176 int R, G, B; 177 178 /* Initial 'P' has already been read by read_color_map */ 179 c = getc(infile); /* save format discriminator for a sec */ 180 181 /* while we fetch the remaining header info */ 182 w = read_pbm_integer(cinfo, infile); 183 h = read_pbm_integer(cinfo, infile); 184 maxval = read_pbm_integer(cinfo, infile); 185 186 if (w <= 0 || h <= 0 || maxval <= 0) /* error check */ 187 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 188 189 /* For now, we don't support rescaling from an unusual maxval. */ 190 if (maxval != (unsigned int) MAXJSAMPLE) 191 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 192 193 switch (c) { 194 case '3': /* it's a text-format PPM file */ 195 for (row = 0; row < h; row++) { 196 for (col = 0; col < w; col++) { 197 R = read_pbm_integer(cinfo, infile); 198 G = read_pbm_integer(cinfo, infile); 199 B = read_pbm_integer(cinfo, infile); 200 add_map_entry(cinfo, R, G, B); 201 } 202 } 203 break; 204 205 case '6': /* it's a raw-format PPM file */ 206 for (row = 0; row < h; row++) { 207 for (col = 0; col < w; col++) { 208 R = getc(infile); 209 G = getc(infile); 210 B = getc(infile); 211 if (R == EOF || G == EOF || B == EOF) 212 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 213 add_map_entry(cinfo, R, G, B); 214 } 215 } 216 break; 217 218 default: 219 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 220 break; 221 } 222 } 223 224 225 /* 226 * Main entry point from djpeg.c. 227 * Input: opened input file (from file name argument on command line). 228 * Output: colormap and actual_number_of_colors fields are set in cinfo. 229 */ 230 231 GLOBAL(void) 232 read_color_map (j_decompress_ptr cinfo, FILE *infile) 233 { 234 /* Allocate space for a color map of maximum supported size. */ 235 cinfo->colormap = (*cinfo->mem->alloc_sarray) 236 ((j_common_ptr) cinfo, JPOOL_IMAGE, 237 (JDIMENSION) (MAXJSAMPLE+1), (JDIMENSION) 3); 238 cinfo->actual_number_of_colors = 0; /* initialize map to empty */ 239 240 /* Read first byte to determine file format */ 241 switch (getc(infile)) { 242 case 'G': 243 read_gif_map(cinfo, infile); 244 break; 245 case 'P': 246 read_ppm_map(cinfo, infile); 247 break; 248 default: 249 ERREXIT(cinfo, JERR_BAD_CMAP_FILE); 250 break; 251 } 252 } 253 254 #endif /* QUANT_2PASS_SUPPORTED */ 255
