If color as we perceive it is dependent on the wave lengths that are reflected by an object, with white reflecting all hues and black absorbing all, how do we detect a black object? I do understand there is no such thing as a perfect black. Is it this physical imperfection of black surfaces that provides the visual system with a cue about its shading?   
If the color black reflects no light, how are we able to see it?
perception;vision;sensation;neurophysiology