1. A method of performing a biometric function, the method comprising: illuminating a purported skin site of an individual with illumination light having a plurality of wavelengths, wherein the purported skin site is in contact with a surface; receiving light scattered from the purported skin site, wherein the light is received substantially in a plane that includes the surface; using a processor to carry out the steps of: forming a plurality of images corresponding to different of the plurality of wavelengths from the received light; generating an image-texture measure from the plurality of images; and analyzing the generated image-texture measure to perform the biometric function.