US Patent 7717630 Lens cap with integral reference surface

A lens cap for a camera is disclosed, comprising: a reference surface, the reference surface having the capability of being used to calibrate an exposure setting or a white balance setting of a photographic subject; wherein the lens cap is placed in front of a lens of the camera in the lighting conditions of the photographic subject, the reference surface being directed towards the lens; and wherein an intensity of the visible light spectrum being reflected by the reference surface is detected.