go/src/image/png/paeth.go

const intSize …

func abs(x int) int { … }

// paeth implements the Paeth filter function, as per the PNG specification.
func paeth(a, b, c uint8) uint8 { … }

// filterPaeth applies the Paeth filter to the cdat slice.
// cdat is the current row's data, pdat is the previous row's data.
func filterPaeth(cdat, pdat []byte, bytesPerPixel int) { … }