}
	defer f.Close()
	return image.DecodeConfig(bufio.NewReader(f))
}

func delta(u0, u1 uint32) int {
	d := int(u0) - int(u1)
	if d < 0 {
		return -d
	}
	return d
}

func withinTolerance(c0, c1 color.Color, tolerance int) bool {
	r0, g0, b0, a0 := c0.RGBA()
	r1, g1, b1, a1 := c1.RGBA()
	r := delta(r0, r1)
	g := delta(g0, g1)
	b := delta(b0, b1)
	a := delta(a0, a1)