go处理jpeg图片例子

test_image.go

package main

import (
	"os"
	"image/color"
	"image/jpeg"
	"image"
	"time"
	"fmt"
)

func main() {
	if len(os.Args) < 3 {
		panic("第一个参数为要处理的文件名，第二个参数为处理后要保存的文件名")
	}
	f, err := os.Open(os.Args[1])
	if err != nil {
		panic(err)
	}
	ts := time.Now()
	ts2 := ts
	img, err2 := jpeg.Decode(f)
	if err2 != nil {
		panic(err2)
	}
	b := img.Bounds()
	w := b.Dx()
	h := b.Dy()
	fmt.Printf("read:\t %dms\n", time.Since(ts) / 1000000)
	ts = time.Now()
	img2 := image.NewRGBA(image.Rect(0, 0, w, h))
	for x := 0; x < w; x++ {
		for y := 0; y < h; y++ {
			r, g, b, a := img.At(x, y).RGBA()
			img2.Set(x, y, color.RGBA{uint8(255 - r >> 8), uint8(255 - g >> 8), uint8(255 - b >> 8), uint8(a >> 8) })
			//img2.Set(x, y, color.White)
		}
	}
	fmt.Printf("convert:\t %dms\n", time.Since(ts) / 1000000)
	ts = time.Now()
	s, err := os.Create(os.Args[2])
	if err != nil {
		panic(err)
	}
	err = jpeg.Encode(s, img2, &jpeg.Options{Quality: 75 })
	if err != nil {
		panic(err)
	}
	fmt.Printf("save:\t %dms\n", time.Since(ts) / 1000000)
	fmt.Printf("total:\t %dms\n", time.Since(ts2) / 1000000)
	fmt.Printf("size:\t %dx%d", w, h)
}

/*
全白
read:	 245ms
convert: 939ms
save:	 281ms
total:	 1466ms
size:	 4032x3024

反色
read:	 251ms
convert: 1341ms
save:	 382ms
total:	 1974ms
size:	 4032x3024
 */