static inline int process_image(void *img, int width, int height, void (*f)(void *, int, int))
{
    int x, y;

    for (y = 0; y < height; y++)
        for (x = 0; x < width; x++)
            f(img, x, y);
}

int process_image_foo(void *img, int width, int height)
{
    return process_image(img, width, height, foo);
}

int process_image_bar(void *img, int width, int height)
{
    return process_image(img, width, height, bar);
}

int process_image_baz(void *img, int width, int height)
{
    return process_image(img, width, height, baz);
}