楽しい（直球）
開発環境
> go version
go version go1.16 darwin/amd64
二値化
package main
import (
"image"
"log"
"os"
"image/color"
"image/jpeg"
)
func main() {
png, err := os.Open("./Lenna.jpeg")
if err != nil {
log.Fatal(err.Error())
}
defer png.Close()
img, err := jpeg.Decode(png)
if err != nil {
log.Fatalln(err.Error())
}
bounds := img.Bounds()
result := image.NewRGBA(bounds)
threshold := 255 / 2
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
for x := bounds.Min.X; x < bounds.Max.X; x++ {
pixel := img.At(x, y)
// それぞれ 16bit に変換される (~0xffff)
r, g, b, a := pixel.RGBA()
// 0xffff -> 0xff
r, g, b, a = r>>8, g>>8, b>>8, a>>8
mean := (r + g + b) / 3
if uint8(mean) >= uint8(threshold) {
col := color.RGBA{R: uint8(255), G: uint8(255), B: uint8(255), A: uint8(0)}
result.Set(x, y, col)
} else {
col := color.RGBA{R: uint8(0), G: uint8(0), B: uint8(0), A: uint8(0)}
result.Set(x, y, col)
}
}
}
quality := &jpeg.Options{Quality: 100}
err = jpeg.Encode(os.Stdout, result, quality)
if err != nil {
log.Fatal(err.Error())
}
}
> go run main.go > hoge.jpg
モザイク
分かりにくいので拡大。
package main
import (
"image"
"log"
"os"
"image/color"
"image/jpeg"
)
func main() {
png, err := os.Open("./Lenna.jpeg")
if err != nil {
log.Fatal(err.Error())
}
defer png.Close()
img, err := jpeg.Decode(png)
if err != nil {
log.Fatalln(err.Error())
}
bounds := img.Bounds()
result := image.NewRGBA(bounds)
var dx []int = []int{-1, -1, 0, 0}
var dy []int = []int{-1, 0, -1, 0}
for y := 1; y < bounds.Max.Y; y += 2 {
for x := 1; x < bounds.Max.X; x += 2 {
var rt uint32 = 0
var gt uint32 = 0
var bt uint32 = 0
for di := 0; di < 4; di++ {
nx := x + dx[di]
ny := y + dy[di]
pixel := img.At(nx, ny)
r, g, b, a := pixel.RGBA()
r, g, b, a = r>>8, g>>8, b>>8, a>>8
rt += r
gt += g
bt += b
}
rm, gm, bm := rt/4, gt/4, bt/4
for di := 0; di < 4; di++ {
nx := x + dx[di]
ny := y + dy[di]
col := color.RGBA{R: uint8(rm), G: uint8(gm), B: uint8(bm), A: uint8(0)}
result.Set(nx, ny, col)
}
}
}
quality := &jpeg.Options{Quality: 100}
err = jpeg.Encode(os.Stdout, result, quality)
if err != nil {
log.Fatal(err.Error())
}
}
実装イメージ
4マスの RGB 値の平均を取って、4マスそれぞれに平均をいれて出力。