Lighten and darken colors in android

ColorUtil

public static int lighten(int color, double fraction) {
		int red = Color.red(color);
		int green = Color.green(color);
		int blue = Color.blue(color);
		red = lightenColor(red, fraction);
		green = lightenColor(green, fraction);
		blue = lightenColor(blue, fraction);
		int alpha = Color.alpha(color);
		return Color.argb(alpha, red, green, blue);
	}

	public static int darken(int color, double fraction) {
		int red = Color.red(color);
		int green = Color.green(color);
		int blue = Color.blue(color);
		red = darkenColor(red, fraction);
		green = darkenColor(green, fraction);
		blue = darkenColor(blue, fraction);
		int alpha = Color.alpha(color);

		return Color.argb(alpha, red, green, blue);
	}

	private static int darkenColor(int color, double fraction) {
		return (int)Math.max(color - (color * fraction), 0);
	}

	private static int lightenColor(int color, double fraction) {
		return (int) Math.min(color + (color * fraction), 255);
	}

Thanks this was helpful.

Not sure this works very well since the r/g/b values are not linearly correlated to their intensity. See https://en.wikipedia.org/wiki/SRGB