PNG を YUV に分解 (Wikipedia に似せる為に UVのデフォルトを 110 に調整)

png_separate_yuv.go

package main

// http://blog.golang.org/go-image-package
// http://d.hatena.ne.jp/taknb2nch/20131231/1388500659

import (
        "flag"
        "fmt"
        "image"
        "image/color"
        "image/png"
        "os"
)

func RGBToYUV(r, g, b uint8) (uint8, uint8, uint8) {
        r1 := float64(r)
        g1 := float64(g)
        b1 := float64(b)
        y := 0.299*r1 + 0.587*g1 + 0.114*b1
        u := -0.14713*r1 - 0.28886*g1 + 0.436*b1 + 128
        v := 0.615*r1 - 0.51499*g1 - 0.10001*b1 + 128
        return uint8(y), uint8(u), uint8(v)
}

func YUVToRGB(y, u, v uint8) (uint8, uint8, uint8) {
        y1 := float64(y)
        u1 := float64(u)
        v1 := float64(v)
        r := y1 + 1.13983*(v1-128)
        g := y1 - 0.39465*(u1-128) - 0.58060*(v1-128)
        b := y1 + 2.03211*(u1-128)
        return uint8(r), uint8(g), uint8(b)
}

func color_YUV(y, u, v uint8) color.RGBA {
        r, g, b := YUVToRGB(y, u, v)
        return color.RGBA{uint8(r), uint8(g), uint8(b), 255}
}

func main() {
        flag.Parse()
        file_in := flag.Arg(0)
        file_out := flag.Arg(1)
        fd_in, err := os.Open(file_in)
        if err != nil {
                fmt.Fprintln(os.Stderr, "not found:"+file_in)
                os.Exit(1)
        }
        fd_out, err := os.Create(file_out)
        if err != nil {
                fmt.Fprintln(os.Stderr, "not found:"+file_out)
                os.Exit(1)
        }
        image_in, _ := png.Decode(fd_in)
        rect := image_in.Bounds()
        size := rect.Size()

        image_out := image.NewNRGBA(image.Rect(0, 0, 3*size.X, size.Y))

        for y := 0; y < size.Y; y++ {
                for x := 0; x < size.X; x++ {
                        var yycolor, uucolor, vvcolor color.Color
                        r, g, b, _ := image_in.At(x, y).RGBA()
                        yy, uu, vv := RGBToYUV(uint8(r), uint8(g), uint8(b))
                        yycolor = color_YUV(uint8(yy), 128, 128)
                        uucolor = color_YUV(130, uint8(uu), 110)
                        vvcolor = color_YUV(130, 110, uint8(vv))
                        image_out.Set(x, y, yycolor)
                        image_out.Set(size.X+x, y, uucolor)
                        image_out.Set(2*size.X+x, y, vvcolor)
                }
        }
        png.Encode(fd_out, image_out)
}