Cone–rod receptor spaces with illustrations that use CRT phosphor and light-emitting-diode spectra

The purpose of the study is to characterize the excitation of the three cone types and the rods in a colorimetric system. Two representations of photoreceptor activity are developed. In the first, rod activity is characterized within a cone colorimetric system that is based on three known physical primaries. Examples are given that use color CRT phosphor spectra. We illustrate how this representation can be used to evaluate the range of chromaticities over which rod signals may intrude into color-monitor-based investigations of cone function. In the second representation, mixtures of four physical primary lights are used to manipulate the four receptor excitations independently. This method allows specification of sets of lights that isolate or silence up to three receptor classes or any combination of receptor classes. Examples are given that use spectra from four light-emitting diodes. This approach opens a field of research in which rod input to various retinal pathways can be evaluated.