The information content of texture gradients.

Texture gradients are systematic variations in projected surface texture. It is expected that image variables such as texture density or size carry information about the surface orientation and distance. This article reexamines the information content of texture gradients and reviews the relevant psychophysics. Slant is shown to be difficult to infer from a texture gradient, but tilt (the direction of slant) is easily and reliably determined. Regarding distance, a new texture measure is introduced that has a simple geometric definition, and from which distance can be readily computed. Variables affecting the precision and the accuracy of the distance computation are discussed.