package main

import (
    images "github.com/mantyr/images-imagick"
    "fmt"
)

func main() {
    address := "file.png"

    image, err := images.Open(address)
    if err != nil {
        fmt.Println(err)
        return
    }

    w := image.Width()
    h := image.Height()
    w = int(w/2)
    h = int(h/2)

    address = "file.gif"

    err = image.ResizeIn(w, h).SetGif().SetQuality(100).Save(address)
    if err != nil {
        fmt.Println(err)
        return
    }
    image.Dispose()  // It is very important, otherwise it will be a memory leak
}