X-Rite (GretagMacbeth) White Balance card

The Xrite ColorChecker Custom White Balance Card is a full size version of the white reference square found on the standard 24-patch ColorChecker Card. This white card 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. The ColorChecker Custom White Balance card gives photographers a way to adjust the digital camera's color sensitivity to match the ambient lighting conditions exactly, in effect, change what that the camera "sees." Even in a controlled studio environment, establishing an accurate custom white balance ensures an accurate image from the start of each new photo session.