| /* |
| * 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 */ |