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lightning-sunbird  0.9+nobinonly
imagediff.c File Reference
#include <stdio.h>
#include <stdlib.h>
#include "buffer_diff.h"
#include "read_png.h"
#include "write_png.h"
#include "xmalloc.h"

Go to the source code of this file.


int main (int argc, char *argv[])

Function Documentation

int main ( int  argc,
char *  argv[] 

Definition at line 35 of file imagediff.c.

    unsigned char *buffer_a;
    unsigned int width_a, height_a, stride_a;
    unsigned char *buffer_b;
    unsigned int width_b, height_b, stride_b;

    unsigned char *buffer;
    unsigned int width, height, stride;
    int buffer_size, total_pixels_changed;

    if (argc < 2) {
       fprintf (stderr, "Usage: %s image1.png image2.png\n", argv[0]);
       fprintf (stderr, "Computes an output image designed to present a \"visual diff\" such that even\n");
       fprintf (stderr, "small errors in single pixels are readily apparent in the output.\n");
       fprintf (stderr, "The output image is written on stdout.\n");
       exit (1);

    read_png_argb32 (argv[1], &buffer_a, &width_a, &height_a, &stride_a);
    read_png_argb32 (argv[2], &buffer_b, &width_b, &height_b, &stride_b);

    if ((width_a == width_b) && (height_a == height_b) && (stride_a == stride_b))
       width = width_a;
       height = height_a;
       stride = stride_a;
    } else {
       fprintf (stderr, "Error. Both images must be the same size\n");
       return 1;

    buffer_size = stride * height;
    buffer = xmalloc (buffer_size);
    total_pixels_changed = buffer_diff (buffer_a, buffer_b, buffer,
                                   width_a, height_a, stride_a);

    if (total_pixels_changed)
       fprintf (stderr, "Total pixels changed: %d\n", total_pixels_changed);
    write_png_argb32 (buffer, stdout, width, height, stride);

    free (buffer);

    return 0;

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