Gray with Ruler
Nr. 19

A medium gray background with a ruler serve as a useful reference between the physically perceptible world and the photographic image. The ruler helps in estimating the size of the object. A background in neutral (!) or medium gray (18% gray) can be used as a reference for light color casts and brightness in the physical scene. The presence of reference aids within the image, such as rulers, can convey to the viewer that the image was created for a context in which a reference is relevant – such as in forensics or science.