add. ·noun a device for giving shifting effects of color to a photograph. the unmounted print, made translucent, is illuminated from behind with colored light.
2. photochromoscope ·add. ·noun a combination of three optical lanterns for projecting objects on a screen in the colors of nature. the images of three partial photographs taken through color screens (red, green, and blue, respectively) are superimposed. each image is given its own primary color, and these colors blend and reproduce the colors of the object.