golang resize image

resize.go

package main

import (
    "os"
    "fmt"
    "github.com/nfnt/resize"
    "image/jpeg"
    "image"
)

func main() {
    f, err := os.Open("original.jpg")
    if err != nil {
        fmt.Println("Error opening file: ", err)
        os.Exit(1)
    }
    defer f.Close()
    original, err := jpeg.Decode(f)

    resizeWidth := float64(200)
    scale := resizeWidth / float64(original.Bounds().Dx())
    width, height := Scale(original.Bounds(), scale)

    img := resize.Resize(uint(width), uint(height), original, resize.Lanczos3)

    resized, err := os.Create("resized.jpg")
    if err != nil {
        fmt.Println("Error creating file: ", err)
        os.Exit(1)
    }
    defer resized.Close()

    // write new image to file
    jpeg.Encode(resized, img, nil)
}

func Scale(image image.Rectangle, scale float64) (width, height uint) {
    return uint(float64(image.Dx()) * scale), uint(float64(image.Dy()) * scale)
}