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