Create a simple png file with fancy colors

gistfile1.go

package main

import (
    "fmt"
    "os"
    "image"
    "image/png"
    "image/color"
)
func paintImage(img *image.RGBA) {
  for x := 0; x < 200; x++ {
    for y := 0; y < 200; y++ {
      img.Set(x, y, color.RGBA{128, uint8(255 - x), uint8(y), 255})
    }
  }
  
}
func main() {
  var i *image.RGBA
  i = image.NewRGBA(image.Rect(0,0, 200, 200))
  
  paintImage(i)
  
  file, ferr := os.OpenFile("test.png", os.O_TRUNC | os.O_CREATE | os.O_WRONLY, 0666)
  fmt.Println(ferr);
  
  err := png.Encode(file, i)
  file.Sync()
  
  fmt.Println(err)
}