A test apparatus comprising a combination of front illuminated and rear illuminated optical reference test elements designed to produce predetermined electronic signals. The front illuminated elements comprise spectrophotometrically neutral gray patches and primary and secondary color patches of predetermined hues. Additional color patches having the same hue as the primaries and secondaries, but at lower saturation levels, generate unique logical patterns on display devices well known to the broadcasting and image reproducing industries. The rear illuminated test elements comprise wide color gamut hues at levels of saturation not attainable in reflected light systems. Also disclosed is a method of evaluating and optimizing the image quality in high gamut imaging systems, using the above described apparatus.