img_conversion.go

// ImgToPix converts an image to an 1D uint8 pixel array.
// In order to preserve the color information per pixel we need to reconstruct the array to a specific format.
func ImgToPix(src *image.NRGBA) []uint8 {
	size := src.Bounds().Size()
	width, height := size.X, size.Y
	pixels := make([][][3]uint8, height)

	for y := 0; y < height; y++ {
		row := make([][3]uint8, width)
		for x := 0; x < width; x++ {
			idx := (y*width + x) * 4
			pix := src.Pix[idx : idx+4]
			row[x] = [3]uint8{uint8(pix[0]), uint8(pix[1]), uint8(pix[2])}
		}
		pixels[y] = row
	}

	// Flatten the 3d array to 1D.
	flattened := []uint8{}
	for x := 0; x < len(pixels); x++ {
		for y := 0; y < len(pixels[x]); y++ {
			r := pixels[x][y][0]
			g := pixels[x][y][1]
			b := pixels[x][y][2]
			flattened = append(flattened, r, g, b, 255)
		}
	}
	return flattened
}

// PixToImage converts the pixel data to an image.
func PixToImage(pixels []uint8, rect image.Rectangle) image.Image {
	img := image.NewNRGBA(rect)
	bounds := img.Bounds()
	dx, dy := bounds.Max.X, bounds.Max.Y
	col := color.NRGBA{}

	for y := bounds.Min.Y; y < dy; y++ {
		for x := bounds.Min.X; x < dx*4; x += 4 {
			col.R = pixels[x+y*dx*4]
			col.G = pixels[x+y*dx*4+1]
			col.B = pixels[x+y*dx*4+2]
			col.A = pixels[x+y*dx*4+3]

			img.SetNRGBA(int(x/4), y, col)
		}
	}
	return img
}