A Simple Grayscale Filter in Golang

Readme.MD

This is a simple grayscale filter implementening image.Image. It can be used in place where an image.Image is expected.

img, err := loadImage("input.jpg")
// check error

err := saveImage(&GrayscaleFilter{img})
//check error

The approach above uses the so-called "luminosity method" for averaging colors

---

P.S. Learn more about this and other Graphics Programming stuff in Go in my book Generative Art in Go.

main.go

type GrayscaleFilter struct {
	image.Image
}

func (f *GrayscaleFilter) At(x, y int) color.Color {
	r, g, b, a := f.Image.At(x, y).RGBA()
	grey := uint16(float64(r)*0.21 + float64(g)*0.72 + float64(b)*0.07)

	return color.RGBA64{
		R: grey,
		G: grey,
		B: grey,
		A: uint16(a),
	}
}