Sometimes also referred to as "black light." The term refers to the fact that projectors cannot produce real black. The reason is that black is defined as the absence of light and the projector will always send out some light regardless of the technology. LCD technology selectively blocks the light that comes from the lamp to produce a picture while DLP technology reflects every pixel with a tiny mirror. Though DLP projectors generally do a better job of producing black, there is always light bouncing inside the projector and between pixels which will be sent out though the lens. Real black can only be achieved by physically blocking the light or by turning off the projector.

The black seen in projections are optical illusions caused by the way the brain processes what the eye sees.