public int getBrightness() {
		return origBrightness;
	}
@param brightness in range [-100..100] where 0 has no effect
@param contrast in range [-100..100] where 0 has no effect
@param alpha in range [0..100] where 0 is transparent, 100 has no effect
flatlaf-core/src/main/java/com/formdev/flatlaf/util/GrayFilter.java