Seam Carving Command line

// seam: resize images using seam carving
package main

import (
	"flag"
	"fmt"
	"image"
	"image/png"
	"image/gif"
	"image/jpeg"
	"os"
	"path"

	"github.com/aaparella/carve"
)

func seam(filename string, size int) error {
	r, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer r.Close()

	img, format, err := image.Decode(r)
	if err != nil {
		return err
	}

	resized, err := carve.ReduceHeight(img, size)
	if err != nil {
		return err
	}

	seamname := path.Join(path.Dir(filename), fmt.Sprintf("seam-%03d-%s", size, path.Base(filename)))

	w, err := os.Create(seamname)
	if err != nil {
		return err
	}
	defer w.Close()


	var werr error
	switch format {
		case "gif":
			werr = gif.Encode(w, resized, nil)
		case "png":
			werr = png.Encode(w, resized)
		case "jpeg":
			werr = jpeg.Encode(w, resized, nil)
		default:
			werr = png.Encode(w, resized)
	}
	return werr

}

func main() {
	var size = flag.Int("size", 50, "pixels to reduce")
	flag.Parse()
	for _, f := range flag.Args() {
		if err := seam(f, *size); err != nil {
			fmt.Fprintf(os.Stderr, "%v\n", err)
			continue
		}
	}
}