A DESCRIPTION OF THE REQUEST :
Just a minor optimization of the darker method.

Each rgb component * FACTOR constant (is 0.7) is allways >=0

Is
public Color darker() {
return new Color(Math.max((int)(getRed() *FACTOR), 0),
Math.max((int)(getGreen()*FACTOR), 0),
Math.max((int)(getBlue() *FACTOR), 0));
    }

Should be
public Color darker() {
return new Color((int)(getRed() *FACTOR),
(int)(getGreen()*FACTOR),
(int)(getBlue() *FACTOR));
    }

JUSTIFICATION :
Speed