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 (colormap0[index] == R && colormap1[index] == G &&
58         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)
read_gif_map(j_decompress_ptr cinfo,FILE * infile)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)
pbm_getc(FILE * infile)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)
read_pbm_integer(j_decompress_ptr cinfo,FILE * infile)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)
read_ppm_map(j_decompress_ptr cinfo,FILE * infile)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)
read_color_map(j_decompress_ptr cinfo,FILE * infile)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