Calculate dissimlarities between the source image and target images.

dissim.go

package main

import (
	"fmt"
	"image"
	"image/png"
	"os"

	"github.com/codegangsta/cli"
	"github.com/mitsuse/mitsuse-go/image/similarity"
)

func main() {
	app := initApp()
	app.Run(os.Args)
}

func initApp() *cli.App {
	app := cli.NewApp()

	app.Name = "dissim"
	app.Version = "0.0.1"
	app.Usage = "Calculate dissimlarities between the source image and target images."

	app.Flags = []cli.Flag{
		cli.StringFlag{
			Name:  "source,s",
			Value: "source.png",
			Usage: "The path of source iamge",
		},
	}
	app.Action = func(context *cli.Context) {
		if err := process(context); err != nil {
			fmt.Fprintf(os.Stderr, "%s: %s\n", app.Name, err)
		}
	}

	return app
}

func process(context *cli.Context) error {
	sourceImg, err := decodeFrom(context.String("source"))
	if err != nil {
		return err
	}

	for _, targetPath := range context.Args() {
		targetImg, err := decodeFrom(targetPath)
		if err != nil {
			return err
		}

		d, err := dissim(sourceImg, targetImg)
		if err != nil {
			return err
		}

		printDissim(targetPath, d)
	}

	return nil
}

func decodeFrom(imgPath string) (image.Image, error) {
	imgFile, err := os.Open(imgPath)
	if err != nil {
		return nil, err
	}
	defer imgFile.Close()

	return png.Decode(imgFile)
}

func dissim(m, n image.Image) (float64, error) {
	return similarity.Dissim(m, n, similarity.AbsoluteDissim)
}

func printDissim(targetPath string, d float64) {
	fmt.Printf("%s\t%f\n", targetPath, d)
}