static int diff_C(unsigned char *old, unsigned char *new, int os, int ns)

{

    int x, y, d=0;

    for (y = 8; y; y--) {

        for (x = 8; x; x--) {

            d += abs(new[x] - old[x]);

        }

        new += ns;

        old += os;

    }

    return d;

}
