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/*
* readpng.c
*
* Read PNG images
*
* (c) 2007 Thomas White <taw27@cam.ac.uk>
*
* dtr - Diffraction Tomography Reconstruction
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <png.h>
#include <math.h>
#include "control.h"
#include "reflections.h"
#include "itrans.h"
int readpng_read(const char *filename, double tilt, ControlContext *ctx) {
FILE *fh;
png_bytep header;
png_structp png_ptr;
png_infop info_ptr;
png_infop end_info;
unsigned int width;
unsigned int height;
unsigned int bit_depth;
unsigned int channels;
png_bytep *row_pointers;
unsigned int x;
unsigned int y;
uint16_t *image;
/* Open file */
fh = fopen(filename, "rb");
if ( !fh ) {
printf("RI: Couldn't open file '%s'\n", filename);
return -1;
}
/* Check it's actually a PNG file */
header = malloc(8);
fread(header, 1, 8, fh);
if ( png_sig_cmp(header, 0, 8)) {
printf("RI: Not a PNG file.\n");
free(header);
fclose(fh);
return -1;
}
free(header);
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if ( !png_ptr ) {
printf("RI: Couldn't create PNG read structure.\n");
fclose(fh);
return -1;
}
info_ptr = png_create_info_struct(png_ptr);
if ( !info_ptr ) {
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
printf("RI: Couldn't create PNG info structure.\n");
fclose(fh);
return -1;
}
end_info = png_create_info_struct(png_ptr);
if ( !end_info ) {
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
printf("RI: Couldn't create PNG end info structure.\n");
fclose(fh);
return -1;
}
if ( setjmp(png_jmpbuf(png_ptr)) ) {
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
fclose(fh);
printf("RI: PNG read failed.\n");
return -1;
}
png_init_io(png_ptr, fh);
png_set_sig_bytes(png_ptr, 8);
/* Read! */
png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_STRIP_ALPHA, NULL);
width = png_get_image_width(png_ptr, info_ptr);
height = png_get_image_height(png_ptr, info_ptr);
bit_depth = png_get_bit_depth(png_ptr, info_ptr);
channels = png_get_channels(png_ptr, info_ptr);
//printf("RI: width=%i, height=%i, depth=%i, channels=%i\n", width, height, bit_depth, channels);
if ( (bit_depth != 16) && (bit_depth != 8) ) {
printf("RI: Whoops! Can't handle images with other than 8 or 16 bpp yet...\n");
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
fclose(fh);
return -1;
}
/* Get image data */
row_pointers = png_get_rows(png_ptr, info_ptr);
image = malloc(height * width * sizeof(uint16_t));
ctx->fmode = FORMULATION_CLEN;
for ( y=0; y<height; y++ ) {
for ( x=0; x<width; x++ ) {
int val = 0;
if ( bit_depth == 16 ) {
int i;
val = 0;
for ( i=0; i<channels; i++ ) {
/* PNG files are big-endian... */
val += row_pointers[y][(channels*x*2)+(2*i)] << 8;
val += row_pointers[y][(channels*x*2)+(2*i)+1];
}
val /= channels;
if ( val > 65535 ) printf("%i\n", val);
}
if ( bit_depth == 8 ) {
int i;
val = 0;
for ( i=0; i<channels; i++ ) {
val += row_pointers[y][(channels*x)+i];
}
val /= channels;
}
image[x + width*(height-1-y)] = val;
}
}
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
fclose(fh);
image_add(ctx->images, image, width, height, tilt, ctx);
return 0;
}
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