1 /*
2 Convert a PBM image into the DjVu Bitonal RLE format
3 described in the csepdjvu(1) documentation
4
5 Copyright (c) 2004 Scott Pakin <scott+pbm@pakin.org>
6
7 All rights reserved.
8
9 Redistribution and use in source and binary forms, with or without
10 modification, are permitted provided that the following conditions
11 are met:
12
13 1. Redistributions of source code must retain the above copyright
14 notice, this list of conditions and the following disclaimer.
15 2. Redistributions in binary form must reproduce the above copyright
16 notice, this list of conditions and the following disclaimer in the
17 documentation and/or other materials provided with the distribution.
18 3. The name of the author may not be used to endorse or promote products
19 derived from this software without specific prior written permission.
20
21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <stdio.h>
34 #include <errno.h>
35 #include <string.h>
36
37 #include "pbm.h"
38
39
40 /* Write a byte to a file and check for errors. */
41 static void
writebyte(FILE * const ofP,unsigned char const c)42 writebyte(FILE * const ofP,
43 unsigned char const c) {
44
45 if (fputc (c, ofP) == EOF)
46 pm_error ("failed to write to the RLE file. Errno=%d (%s)",
47 errno, strerror(errno));
48 }
49
50
51 /* Write a run length to the RLE file. */
52 static void
write_rle(FILE * const rlefile,uint32_t const tallyArg)53 write_rle(FILE * const rlefile,
54 uint32_t const tallyArg) {
55
56 uint32_t remainingTally;
57
58 remainingTally = tallyArg; /* initial value */
59
60 do {
61 /* Output a single run. */
62 if (remainingTally < 192) {
63 /* Single-byte runs */
64 writebyte (rlefile, remainingTally);
65 remainingTally >>= 8;
66 }
67 else {
68 /* Two-byte runs */
69 writebyte (rlefile, ((remainingTally>>8) & 0x3F) + 0xC0);
70 writebyte (rlefile, remainingTally & 0xFF);
71 remainingTally >>= 14;
72 }
73
74 /* Very large runs need to be split into smaller runs. We
75 therefore need to toggle back to the same color we had for the
76 previous smaller run.
77 */
78 if (remainingTally > 0)
79 writebyte (rlefile, 0);
80 }
81 while (remainingTally > 0);
82 }
83
84
85
86 int
main(int argc,const char * argv[])87 main (int argc, const char * argv[]) {
88
89 FILE * const rlefile = stdout; /* Generated Bitonal RLE file */
90
91 FILE * pbmfile; /* PBM file to convert */
92 int numcols, numrows; /* Width and height in pixels of the PBM file */
93 int format; /* Original image type before conversion to PBM */
94 bit * pbmrow; /* One row of the PBM file */
95 unsigned int row;
96 const char * pbmfilename; /* Name of input file */
97
98 pm_proginit(&argc, argv);
99
100 if (argc-1 < 1)
101 pbmfilename = "-";
102 else if (argc-1 == 1)
103 pbmfilename = argv[1];
104 else
105 pm_error("Program takes at most 1 argument -- the input file name. "
106 "You specified %d", argc-1);
107
108 pbmfile = pm_openr(pbmfilename);
109
110 /* Write an RLE header. */
111 pbm_readpbminit(pbmfile, &numcols, &numrows, &format);
112 fprintf(rlefile, "R4\n");
113 fprintf(rlefile, "%d %d\n", numcols, numrows);
114
115 /* Write the RLE data. */
116 pbmrow = pbm_allocrow(numcols);
117 for (row = 0; row < numrows; ++row) {
118 unsigned int col;
119 uint32_t pixeltally; /* Run length of the current color */
120 bit prevpixel; /* Previous pixel seen */
121
122 pbm_readpbmrow(pbmfile, pbmrow, numcols, format);
123 prevpixel = PBM_WHITE; /* Bitonal RLE rows always start with white */
124 pixeltally = 0;
125 for (col = 0; col < numcols; ++col) {
126 bit newpixel = pbmrow[col]; /* Current pixel color */
127
128 if (newpixel == prevpixel)
129 ++pixeltally;
130 else {
131 write_rle(rlefile, pixeltally);
132 pixeltally = 1;
133 prevpixel = newpixel;
134 }
135 }
136 write_rle(rlefile, pixeltally);
137 }
138
139 pbm_freerow(pbmrow);
140 if (rlefile != stdout)
141 pm_close(rlefile);
142 if (pbmfile != stdin)
143 pm_close(pbmfile);
144
145 return 0;
146 }
147