Projectors do not project the color black. This makes sense since black is really the absence of light, and you can't project something that does not exist. When a projector sends a beam of light on to a wall or a projector screen so that an image is formed on the wall or screen, the parts of the image that look black are really a very dim white color (which we sometimes call gray). The projector sends some light to all parts of the image, including the parts that we perceive as black. Some white light is indeed beamed to the parts of the image that are supposed to be black, but the light is typically dim enough in these regions that they look black to our eyes when surrounded by areas of the image that are receiving much more light and therefore are much brighter.