source: trunk/third/jpeg/rdcolmap.c @ 15227

Revision 15227, 6.7 KB checked in by ghudson, 24 years ago (diff)
This commit was generated by cvs2svn to compensate for changes in r15226, which included commits to RCS files with non-trunk default branches.
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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 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
45LOCAL(void)
46add_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
78LOCAL(void)
79read_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
120LOCAL(int)
121pbm_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
137LOCAL(unsigned int)
138read_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
170LOCAL(void)
171read_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
230GLOBAL(void)
231read_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 */
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