blob: f9d5138b7eb180fab78cf006c6288e51a5a74a77 [file] [log] [blame] [edit]
/*
* png2pnm.c --- conversion from PNG-file to PGM/PPM-file
* copyright (C) 1999-2019 by Willem van Schaik <willem at schaik dot com>
*
* This software is released under the MIT license. For conditions of
* distribution and use, see the LICENSE file part of this package.
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#ifndef BOOL
#define BOOL unsigned char
#endif
#ifndef TRUE
#define TRUE ((BOOL) 1)
#endif
#ifndef FALSE
#define FALSE ((BOOL) 0)
#endif
#include "png.h"
/* function prototypes */
int main (int argc, char *argv[]);
void usage ();
BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
BOOL raw, BOOL alpha);
BOOL do_png2pnm (png_struct *png_ptr, png_info *info_ptr,
FILE *pnm_file, FILE *alpha_file,
BOOL raw, BOOL alpha);
/*
* main
*/
int main (int argc, char *argv[])
{
FILE *fp_rd = stdin;
FILE *fp_wr = stdout;
FILE *fp_al = NULL;
const char *fname_wr = NULL;
const char *fname_al = NULL;
BOOL raw = TRUE;
BOOL alpha = FALSE;
int argi;
int ret;
for (argi = 1; argi < argc; argi++)
{
if (argv[argi][0] == '-')
{
switch (argv[argi][1])
{
case 'n':
raw = FALSE;
break;
case 'r':
raw = TRUE;
break;
case 'a':
alpha = TRUE;
argi++;
if ((fp_al = fopen (argv[argi], "wb")) == NULL)
{
fname_al = argv[argi];
fprintf (stderr, "PNM2PNG\n");
fprintf (stderr, "Error: cannot create alpha-channel file %s\n",
argv[argi]);
exit (1);
}
break;
case 'h':
case '?':
usage ();
exit (0);
break;
default:
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
usage ();
exit (1);
break;
} /* end switch */
}
else if (fp_rd == stdin)
{
if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
exit (1);
}
}
else if (fp_wr == stdout)
{
fname_wr = argv[argi];
if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Error: cannot create file %s\n", argv[argi]);
exit (1);
}
}
else
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Error: too many parameters\n");
usage ();
exit (1);
}
} /* end for */
#if defined(O_BINARY) && (O_BINARY != 0)
/* set stdin/stdout if required to binary */
if (fp_rd == stdin)
setmode (fileno (stdin), O_BINARY);
if ((raw) && (fp_wr == stdout))
setmode (fileno (stdout), O_BINARY);
#endif
/* call the conversion program itself */
ret = png2pnm (fp_rd, fp_wr, fp_al, raw, alpha);
/* close input file */
fclose (fp_rd);
/* close output file */
fclose (fp_wr);
/* close alpha file */
if (alpha)
fclose (fp_al);
if (!ret)
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");
if (fname_wr)
remove (fname_wr); /* no broken output file shall remain behind */
if (fname_al)
remove (fname_al); /* ditto */
exit (1);
}
return 0;
}
/*
* usage
*/
void usage ()
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, " by Willem van Schaik, 1999\n");
fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");
fprintf (stderr, " or: ... | png2pnm [options]\n");
fprintf (stderr, "Options:\n");
fprintf (stderr,
" -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");
fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");
fprintf (stderr,
" -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");
fprintf (stderr, " -h | -? print this help-information\n");
}
/*
* png2pnm
*/
BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
BOOL raw, BOOL alpha)
{
png_struct *png_ptr;
png_info *info_ptr;
BOOL ret;
/* initialize the libpng context for reading from png_file */
png_ptr = png_create_read_struct (png_get_libpng_ver(NULL),
NULL, NULL, NULL);
if (!png_ptr)
return FALSE; /* out of memory */
info_ptr = png_create_info_struct (png_ptr);
if (!info_ptr)
{
png_destroy_read_struct (&png_ptr, NULL, NULL);
return FALSE; /* out of memory */
}
if (setjmp (png_jmpbuf (png_ptr)))
{
png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
return FALSE; /* generic libpng error */
}
png_init_io (png_ptr, png_file);
/* do the actual conversion */
ret = do_png2pnm (png_ptr, info_ptr, pnm_file, alpha_file, raw, alpha);
/* clean up the libpng structures and their internally-managed data */
png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
return ret;
}
/*
* do_png2pnm - does the conversion in a fully-initialized libpng context
*/
BOOL do_png2pnm (png_struct *png_ptr, png_info *info_ptr,
FILE *pnm_file, FILE *alpha_file,
BOOL raw, BOOL alpha)
{
png_byte **row_pointers;
png_byte *pix_ptr;
png_uint_32 width;
png_uint_32 height;
int bit_depth;
int channels;
int color_type;
int alpha_present;
png_uint_32 row, col, i;
long dep_16;
/* set up the image transformations that are necessary for the PNM format */
/* set up (if applicable) the expansion of paletted images to full-color rgb,
* and the expansion of transparency maps to full alpha-channel */
png_set_expand (png_ptr);
/* set up (if applicable) the expansion of grayscale images to bit-depth 8 */
png_set_expand_gray_1_2_4_to_8 (png_ptr);
#ifdef NJET
/* downgrade 16-bit images to 8-bit */
if (bit_depth == 16)
png_set_strip_16 (png_ptr);
/* transform grayscale images into full-color */
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb (png_ptr);
/* if the PNG image has a gAMA chunk then gamma-correct the output image */
{
double file_gamma;
if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
png_set_gamma (png_ptr, (double) 2.2, file_gamma);
}
#endif
/* read the image file, with all of the above image transforms applied */
png_read_png (png_ptr, info_ptr, 0, NULL);
/* get the image size, bit-depth and color-type */
png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
NULL, NULL, NULL);
/* calculate the number of channels and store alpha-presence */
if (color_type == PNG_COLOR_TYPE_GRAY)
channels = 1;
else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
channels = 2;
else if (color_type == PNG_COLOR_TYPE_RGB)
channels = 3;
else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
channels = 4;
else
channels = 0; /* should never happen */
alpha_present = (channels - 1) % 2;
/* check if alpha is expected to be present in file */
if (alpha && !alpha_present)
{
fprintf (stderr, "PNG2PNM\n");
fprintf (stderr, "Warning: no alpha channel in PNG file\n");
return FALSE;
}
/* get address of internally-allocated image data */
row_pointers = png_get_rows (png_ptr, info_ptr);
/* write header of PNM file */
if ((color_type == PNG_COLOR_TYPE_GRAY) ||
(color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
{
fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");
fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
}
else if ((color_type == PNG_COLOR_TYPE_RGB) ||
(color_type == PNG_COLOR_TYPE_RGB_ALPHA))
{
fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");
fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
}
/* write header of PGM file with alpha channel */
if ((alpha) &&
((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
(color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
{
fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");
fprintf (alpha_file, "%d %d\n", (int) width, (int) height);
fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
}
/* write data to PNM file */
for (row = 0; row < height; row++)
{
pix_ptr = row_pointers[row];
for (col = 0; col < width; col++)
{
for (i = 0; i < (png_uint_32) (channels - alpha_present); i++)
{
if (raw)
{
fputc ((int) *pix_ptr++, pnm_file);
if (bit_depth == 16)
fputc ((int) *pix_ptr++, pnm_file);
}
else
{
if (bit_depth == 16)
{
dep_16 = ((long) *pix_ptr++) << 8;
dep_16 += ((long) *pix_ptr++);
fprintf (pnm_file, "%ld ", dep_16);
}
else
{
fprintf (pnm_file, "%ld ", (long) *pix_ptr++);
}
}
}
if (alpha_present)
{
if (!alpha)
{
/* skip the alpha-channel */
pix_ptr++;
if (bit_depth == 16)
pix_ptr++;
}
else
{
/* output the alpha-channel as pgm file */
if (raw)
{
fputc ((int) *pix_ptr++, alpha_file);
if (bit_depth == 16)
fputc ((int) *pix_ptr++, alpha_file);
}
else
{
if (bit_depth == 16)
{
dep_16 = ((long) *pix_ptr++) << 8;
dep_16 += ((long) *pix_ptr++);
fprintf (alpha_file, "%ld ", dep_16);
}
else
{
fprintf (alpha_file, "%ld ", (long) *pix_ptr++);
}
}
}
} /* end if alpha_present */
if (!raw)
if (col % 4 == 3)
fprintf (pnm_file, "\n");
} /* end for col */
if (!raw)
if (col % 4 != 0)
fprintf (pnm_file, "\n");
} /* end for row */
return TRUE;
} /* end of source */