 LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums.LCOS and modified LCOS projectors have improved on LCD contrast ratios while also eliminating the “screen door” effect of small gaps between LCD pixels.“Dark chip” DLP projectors improve on the standard DLP design and can offer a relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors.