img := image.NewRGBA(image.Rect(0, 0, width, height))
	for y := 0; y < height; y++ {
		for x := 0; x < width; x++ {
			percent := (x + y) % 100
			switch {
			case percent < 10: // 10% of pixels are translucent (have alpha >0 and <255)
				img.Set(x, y, color.NRGBA{uint8(x), uint8(y), uint8(x * y), uint8(percent)})
			case percent < 40: // 30% of pixels are transparent (have alpha == 0)