"PNG" to Ordered Pairs

orderedpairs.c

#include "image.h"
#include <stdio.h>

int main (void) {
    int column;
    int row;
    char *data;
    int pixel[4];
    
    data=header_data;
    
    for (row=0; row<height; row++) {
        for (column=0; column<width; column++) {
            HEADER_PIXEL(data,pixel);
            if (pixel[0]==0) {
                printf ("(%d,-%d)\n", column, row);
            }
        }
    }
    
    return 0;
}