428 lines
11 KiB
C
428 lines
11 KiB
C
/*
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* png2pnm.c --- conversion from PNG-file to PGM/PPM-file
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* copyright (C) 1999-2019 by Willem van Schaik <willem at schaik dot com>
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*
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* This software is released under the MIT license. For conditions of
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* distribution and use, see the LICENSE file part of this package.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#ifndef BOOL
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#define BOOL unsigned char
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#endif
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#ifndef TRUE
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#define TRUE (BOOL) 1
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#endif
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#ifndef FALSE
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#define FALSE (BOOL) 0
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#endif
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/* make png2pnm verbose so we can find problems (needs to be before png.h) */
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#ifndef PNG_DEBUG
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#define PNG_DEBUG 0
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#endif
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#include "png.h"
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/* function prototypes */
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int main (int argc, char *argv[]);
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void usage ();
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BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
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BOOL raw, BOOL alpha);
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/*
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* main
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*/
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int main (int argc, char *argv[])
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{
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FILE *fp_rd = stdin;
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FILE *fp_wr = stdout;
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FILE *fp_al = NULL;
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BOOL raw = TRUE;
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BOOL alpha = FALSE;
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int argi;
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for (argi = 1; argi < argc; argi++)
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{
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if (argv[argi][0] == '-')
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{
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switch (argv[argi][1])
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{
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case 'n':
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raw = FALSE;
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break;
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case 'r':
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raw = TRUE;
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break;
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case 'a':
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alpha = TRUE;
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argi++;
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if ((fp_al = fopen (argv[argi], "wb")) == NULL)
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{
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fprintf (stderr, "PNM2PNG\n");
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fprintf (stderr, "Error: cannot create alpha-channel file %s\n",
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argv[argi]);
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exit (1);
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}
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break;
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case 'h':
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case '?':
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usage ();
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exit (0);
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break;
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default:
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
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usage ();
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exit (1);
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break;
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} /* end switch */
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}
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else if (fp_rd == stdin)
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{
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if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
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exit (1);
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}
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}
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else if (fp_wr == stdout)
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{
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if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: cannot create file %s\n", argv[argi]);
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exit (1);
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}
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}
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else
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: too many parameters\n");
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usage ();
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exit (1);
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}
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} /* end for */
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#if defined(O_BINARY) && (O_BINARY != 0)
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/* set stdin/stdout if required to binary */
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if (fp_rd == stdin)
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setmode (fileno (stdin), O_BINARY);
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if ((raw) && (fp_wr == stdout))
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setmode (fileno (stdout), O_BINARY);
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#endif
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/* call the conversion program itself */
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if (png2pnm (fp_rd, fp_wr, fp_al, raw, alpha) == FALSE)
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");
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exit (1);
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}
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/* close input file */
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fclose (fp_rd);
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/* close output file */
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fclose (fp_wr);
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/* close alpha file */
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if (alpha)
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fclose (fp_al);
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return 0;
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}
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/*
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* usage
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*/
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void usage ()
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, " by Willem van Schaik, 1999\n");
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fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");
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fprintf (stderr, " or: ... | png2pnm [options]\n");
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fprintf (stderr, "Options:\n");
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fprintf (stderr,
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" -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");
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fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");
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fprintf (stderr,
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" -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");
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fprintf (stderr, " -h | -? print this help-information\n");
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}
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/*
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* png2pnm
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*/
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BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
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BOOL raw, BOOL alpha)
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{
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png_struct *png_ptr = NULL;
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png_info *info_ptr = NULL;
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png_byte buf[8];
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png_byte *png_pixels = NULL;
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png_byte **row_pointers = NULL;
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png_byte *pix_ptr = NULL;
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png_uint_32 row_bytes;
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png_uint_32 width;
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png_uint_32 height;
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int bit_depth;
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int channels;
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int color_type;
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int alpha_present;
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int row, col;
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int ret;
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int i;
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long dep_16;
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/* read and check signature in PNG file */
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ret = fread (buf, 1, 8, png_file);
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if (ret != 8)
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return FALSE;
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ret = png_sig_cmp (buf, 0, 8);
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if (ret != 0)
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return FALSE;
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/* create png and info structures */
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png_ptr = png_create_read_struct (png_get_libpng_ver(NULL),
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NULL, NULL, NULL);
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if (!png_ptr)
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return FALSE; /* out of memory */
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info_ptr = png_create_info_struct (png_ptr);
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if (!info_ptr)
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{
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png_destroy_read_struct (&png_ptr, NULL, NULL);
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return FALSE; /* out of memory */
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}
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if (setjmp (png_jmpbuf (png_ptr)))
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{
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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return FALSE;
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}
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/* set up the input control for C streams */
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png_init_io (png_ptr, png_file);
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png_set_sig_bytes (png_ptr, 8); /* we already read the 8 signature bytes */
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/* read the file information */
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png_read_info (png_ptr, info_ptr);
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/* get size and bit-depth of the PNG-image */
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png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
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NULL, NULL, NULL);
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/* set-up the transformations */
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/* transform paletted images into full-color rgb */
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if (color_type == PNG_COLOR_TYPE_PALETTE)
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png_set_expand (png_ptr);
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/* expand images to bit-depth 8 (only applicable for grayscale images) */
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if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
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png_set_expand (png_ptr);
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/* transform transparency maps into full alpha-channel */
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if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
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png_set_expand (png_ptr);
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#ifdef NJET
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/* downgrade 16-bit images to 8-bit */
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if (bit_depth == 16)
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png_set_strip_16 (png_ptr);
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/* transform grayscale images into full-color */
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if (color_type == PNG_COLOR_TYPE_GRAY ||
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color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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png_set_gray_to_rgb (png_ptr);
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/* only if file has a file gamma, we do a correction */
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if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
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png_set_gamma (png_ptr, (double) 2.2, file_gamma);
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#endif
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/* all transformations have been registered; now update info_ptr data,
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* get rowbytes and channels, and allocate image memory */
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png_read_update_info (png_ptr, info_ptr);
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/* get the new color-type and bit-depth (after expansion/stripping) */
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png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
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NULL, NULL, NULL);
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/* check for 16-bit files */
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if (bit_depth == 16)
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{
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raw = FALSE;
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#if defined(O_BINARY) && (O_BINARY != 0)
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setmode (fileno (pnm_file), O_BINARY);
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#endif
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}
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/* calculate new number of channels and store alpha-presence */
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if (color_type == PNG_COLOR_TYPE_GRAY)
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channels = 1;
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else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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channels = 2;
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else if (color_type == PNG_COLOR_TYPE_RGB)
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channels = 3;
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else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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channels = 4;
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else
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channels = 0; /* should never happen */
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alpha_present = (channels - 1) % 2;
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/* check if alpha is expected to be present in file */
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if (alpha && !alpha_present)
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{
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fprintf (stderr, "PNG2PNM\n");
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fprintf (stderr, "Error: PNG-file doesn't contain alpha channel\n");
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exit (1);
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}
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/* row_bytes is the width x number of channels x (bit-depth / 8) */
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row_bytes = png_get_rowbytes (png_ptr, info_ptr);
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if ((row_bytes == 0) ||
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((size_t) height > (size_t) (-1) / (size_t) row_bytes))
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{
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/* too big */
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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return FALSE;
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}
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if ((png_pixels = (png_byte *)
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malloc ((size_t) row_bytes * (size_t) height)) == NULL)
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{
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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return FALSE;
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}
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if ((row_pointers = (png_byte **)
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malloc ((size_t) height * sizeof (png_byte *))) == NULL)
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{
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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free (png_pixels);
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return FALSE;
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}
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/* set the individual row_pointers to point at the correct offsets */
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for (i = 0; i < ((int) height); i++)
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row_pointers[i] = png_pixels + i * row_bytes;
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/* now we can go ahead and just read the whole image */
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png_read_image (png_ptr, row_pointers);
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/* read rest of file, and get additional chunks in info_ptr - REQUIRED */
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png_read_end (png_ptr, info_ptr);
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/* clean up after the read, and free any memory allocated - REQUIRED */
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png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
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/* write header of PNM file */
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if ((color_type == PNG_COLOR_TYPE_GRAY) ||
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(color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
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{
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fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");
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fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
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fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
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}
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else if ((color_type == PNG_COLOR_TYPE_RGB) ||
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(color_type == PNG_COLOR_TYPE_RGB_ALPHA))
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{
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fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");
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fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
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fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
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}
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/* write header of PGM file with alpha channel */
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if ((alpha) &&
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((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
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(color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
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{
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fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");
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fprintf (alpha_file, "%d %d\n", (int) width, (int) height);
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fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
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}
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/* write data to PNM file */
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pix_ptr = png_pixels;
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for (row = 0; row < (int) height; row++)
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{
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for (col = 0; col < (int) width; col++)
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{
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for (i = 0; i < (channels - alpha_present); i++)
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{
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if (raw)
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{
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fputc ((int) *pix_ptr++, pnm_file);
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}
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else
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{
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if (bit_depth == 16)
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{
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dep_16 = (long) *pix_ptr++;
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fprintf (pnm_file, "%ld ", (dep_16 << 8) + ((long) *pix_ptr++));
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}
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else
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{
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fprintf (pnm_file, "%ld ", (long) *pix_ptr++);
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}
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}
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}
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if (alpha_present)
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{
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if (!alpha)
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{
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pix_ptr++; /* alpha */
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if (bit_depth == 16)
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pix_ptr++;
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}
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else /* output alpha-channel as pgm file */
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{
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if (raw)
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{
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fputc ((int) *pix_ptr++, alpha_file);
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}
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else
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{
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if (bit_depth == 16)
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{
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dep_16 = (long) *pix_ptr++;
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fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);
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}
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else
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{
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fprintf (alpha_file, "%ld ", (long) *pix_ptr++);
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}
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}
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}
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} /* end if alpha_present */
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if (!raw)
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if (col % 4 == 3)
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fprintf (pnm_file, "\n");
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} /* end for col */
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if (!raw)
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if (col % 4 != 0)
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fprintf (pnm_file, "\n");
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} /* end for row */
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if (row_pointers != NULL)
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free (row_pointers);
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if (png_pixels != NULL)
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free (png_pixels);
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return TRUE;
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} /* end of source */
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