package main

import (
	"bytes"
	"fmt"
	"image/gif"
	"image/jpeg"
	"io/ioutil"
	"os"
)

func main() {
	f, err := os.Open("test.gif")
	if err != nil {
		panic(err)
	}
	defer f.Close()
	g, err := gif.DecodeAll(f)
	if err != nil {
		panic(err)
	}
	fmt.Println("gif has", len(g.Image), "frames")
	var buf bytes.Buffer
	if err := jpeg.Encode(&buf, g.Image[18], nil); err != nil {
		panic(err)
	}
	ioutil.WriteFile("18th_frame.jpg", buf.Bytes(), 0660)
}