import github/chi-chu/imagescaling

func main(){
    imageData, err := os.Open("/your/image/path/filename.jpg")
    if err != nil {
        panic(err)
    }
    defer imageData.Close()
    img, err := imagescaling.New(imageData)
    if err != nil {
        panic(err)
    }
    outPutPath := "/your/output/image/path/filename."+ img.GetExt()
    fd, err := os.OpenFile(outPutPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0777)
    if err != nil {
        panic(err)
    }
    defer fd.Close()
    err = img.CustomClip(100, 23, 400, 300).FixScale(100, 0).Rotate(imagescaling.Rotate90Degrees).Draw(fd)
    if err != nil {
        panic(err)
    }
}