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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)
add_map_entry(j_decompress_ptr cinfo,int R,int G,int B)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)
read_gif_map(j_decompress_ptr cinfo,FILE * infile)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)
pbm_getc(FILE * infile)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)
read_pbm_integer(j_decompress_ptr cinfo,FILE * infile)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)
read_ppm_map(j_decompress_ptr cinfo,FILE * infile)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)
read_color_map(j_decompress_ptr cinfo,FILE * infile)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