Object

Although we began with a discussion of how an object’s color is perceived, we have delayed discussion of the object itself, since an object is not required in order to perceive color. As we have seen, color can be perceived by an observer receiving energy directly from an illuminant. Recall the CRT: red, green and blue illuminants stimulate the eye essentially simultaneously with no object in between.

Objects reflect, transmit, and absorb light energy. An object through which the majority of light passes is either transparent or translucent; an opaque object, on the other hand, both reflects and absorbs some percent of the light which strikes them. In general, light is reflected diffusely from within the surface layers of an object; some light, however, is directly reflected at an angle opposite to its incident angle. An observer usually sees an object at some other angle: this is important—the angle at which the observer views the object may change the perceived color. As a result, standards for density and color measurement are required. The established convention is perpendicular measurement using 45° illumination.