Domain of metamers exciting intrinsically photosensitive retinal ganglion cells (ipRGCs) and rods.

Any stimulus can be described as composed of two components-a fundamental color stimulus that controls the three cone responses and a metameric black that has no effect on cones but can drive photoreceptors other than cones [e.g., rods and melanopsin expressing retinal ganglion cells (ipRGCs)]. The Cohen and Kappauf [Am. J. Psychol. 95, 537 (1982)] method is extended to calculate the black metamer basis for a limited set of band spectra. Using seven colored LEDs, the method is exploited to produce real metamer illuminations that stimulate in parallel melanopsin expressing ipRGCs and rods, at most or at least. We have verified that the pupil diameter increases when the ipRGC and rod excitation is at a minimum. For 14 observers, the average relative increase is 12%.