https://tour.golang.org/methods/25

exercise-images.go

package main

import (
	"golang.org/x/tour/pic"
	"image"
	"image/color"
)

type Image struct {
	Width, Height int
}

func r(x, y int) uint8 {
	return (uint8(x) + uint8(y)) / 2
}

func g(x, y int) uint8 {
	return uint8(x) * uint8(y)	
}

func b(x, y int) uint8 {
	return uint8(x) ^ uint8(y)	
}


func (img Image) ColorModel() color.Model {
	return color.RGBAModel
}

func (img Image) Bounds() image.Rectangle {
	return image.Rect(0, 0, img.Width, img.Height)
}

func (img Image) At(x, y int) color.Color {
	return color.RGBA{r(x, y), g(x, y), b(x, y), 255}
}

func main() {
	m := Image{100, 100}
	pic.ShowImage(m)
}