Get a single dimensional color.Color list (array) from an image.Image and vice versa.

imageToColors.go

func imageToColors(img image.Image) []color.Color {
	rect := img.Bounds()
	width := rect.Dx()
	height := rect.Dy()
	xFrom := rect.Min.X
	xTo := rect.Max.X
	yFrom := rect.Max.Y - 1
	yTo := rect.Min.Y - 1

	ret := make([]color.Color, width*height)
	for y := yFrom; y > yTo; y-- {
		for x := xFrom; x < xTo; x++ {
			ret[((yFrom-y)*width)+x] = img.At(x, y)
		}
	}
	return ret
}

func colorsToImage(colors []color.Color, width, height int) *image.NRGBA {
	ret := image.NewNRGBA(image.Rect(0, 0, width, height))
	for i, color := range colors {
		col := i % width
		row := (height - 1) - (i-col)/width
		ret.Set(col, row, color)
	}
	return ret
}