1. A method for modifying a first color image or rendition of a scene obtained under a first scene illumination, the method comprising: in a second scene illumination, illuminating at least a portion of the scene with light having a known spectral power distribution; detecting a spectral response of the scene to the light having a known spectral power distribution under the second scene illumination; in third or more scene illuminations, illuminating the same or other portions of the scene with lights having known spectral power distributions; detecting spectral responses of the scene to the lights having the known spectral power distributions under third or more scene illuminations; and modifying the first color image according to the detected spectral response of the scene to the light having a known spectral power distribution under the second scene illumination and under the third or more scene illuminations.