Basic image sample in Go

gistfile1.go

package main

import (
    "fmt"
    "image"
    "image/color"
    "image/png"
    "os"
)

var width = 256
var height = 256

func main() {
    img := image.NewRGBA(image.Rect(0, 0, width, height))
    for y := 0; y < height; y++ {
        for x := 0; x < width; x++ {
            img.Set(x, y, color.RGBA{uint8(x), uint8(y), uint8((x + y) / 2), 255})
        }
    }

    f, e := os.OpenFile("sample.png", os.O_WRONLY | os.O_CREATE, 0666)
    if e != nil {
        fmt.Println(e)
        return
    }
    defer f.Close()

    png.Encode(f, img)
}