STATISTICS OF CONE RESPONSES TO NATURAL IMAGES - IMPLICATIONS FOR VISUAL CODING

We gathered hyperspectral images of natural, foliage-dominated scenes and converted them to human cone quantal catches to characterize the s econd-order redundancy present within the retinal photoreceptor array under natural conditions. The data are expressed most simply in a loga rithmic response space, wherein an orthogonal decorrelation robustly p roduces three principal axes, one corresponding to simple changes in r adiance and two that are reminiscent of the blue-yellow and red-green chromatic-opponent mechanisms found in the primate visual system. Furt her inclusion of spatial stimulus dimensions demonstrates a complete s patial decorrelation of these three cone-space axes in natural cone re sponses. (C) 1998 Optical Society of America.