golang invert png images in current folder

main.go

package main

import (
	"io/ioutil"
	"log"
	"github.com/disintegration/imaging"
	"image"
	"os"
)



func main() {
	files, err := ioutil.ReadDir(".")
	if err != nil {
		log.Fatal(err)
	}

	for _, file := range files {
		if len(file.Name()) > 4  && file.Name()[len(file.Name())-4:] == ".png" {
			fio, err := os.Open(file.Name())
			if err!= nil {
				log.Println(err)
				return
			}
			ip, str, err := image.Decode(fio)
			if err!= nil {
				log.Println(str, err)
			}
			inverted := imaging.Invert(ip)
			imaging.Save(inverted,"./inverted/"+file.Name())

		}

	}
}