image_binarize.go

package main

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

func main() {
	var inFile *os.File
	var outFile *os.File
	var img image.Image
	var err error

	if len(os.Args) < 2 {
		log.Fatal()
	}

	for i := 1; i < len(os.Args); i++ {
		filename := os.Args[i]

		if inFile, err = os.Open(filename); err != nil {
			log.Fatal(err)
		}

		if img, err = png.Decode(inFile); err != nil {
			log.Fatal(err)
		}

		defer inFile.Close()

		out_filename := "bin_" + filename[0:len(filename)-4] + ".png"

		if outFile, err = os.Create(out_filename); err != nil {
			log.Fatal(err)
		}

		img = binarize(&img, 100, 255, 0)

		if err = png.Encode(outFile, img); err != nil {
			fmt.Println()
			return
		}
	}
}

func binarize(in *image.Image, th, th_h, th_l uint32) image.Image {
	rect := (*in).Bounds()
	out := image.NewGray(rect)

	for h := 0; h < rect.Max.X; h++ {
		for w := 0; w < rect.Max.Y; w++ {
			c := (*in).At(h, w)
			pel, _, _, _ := c.RGBA()
			pel = pel >> 8
			if pel > th {
				pel = th_h
			} else {
				pel = th_l
			}
			out.Set(h, w, color.Gray{uint8(pel)})
		}
	}
	return out
}