want := slowPaeth(uint8(a), uint8(b), uint8(c))
				if got != want {
					t.Errorf("a, b, c = %d, %d, %d: got %d, want %d", a, b, c, got, want)
				}
			}
		}
	}
}

func BenchmarkPaeth(b *testing.B) {
	for i := 0; i < b.N; i++ {
		paeth(uint8(i>>16), uint8(i>>8), uint8(i))
	}
}

func TestPaethDecode(t *testing.T) {
	pdat0 := make([]byte, 32)
	pdat1 := make([]byte, 32)