The ColorChecker Gray Scale card is a full size version of the white, 18% gray and black reference square used in the standard 24-patch ColorChecker. This target is scientifically engineered to provide a precise uniform surface that is spectrally neutral (reflects equal amounts of red, blue and green) in all types of light conditions. In addition, the ColorChecker Gray Scale provides reference values that can quickly be checked and used to adjust colors within most common photo processing software packages.