LCD - Liquid-crystal display. System used on many DTVs, clocks, answering machines, handheld organizers, camcorders, and personal computers. Liquid crystals are sandwiched between two glass plates. Minor temperature variations are introduced to particular points in the display using pinpoint electric charges, illuminating or causing the crystals to change colors in predetermined patterns.

LCD TV - A television that employs a liquid-crystal display screen rather than a CRT; used in small, personal TVs, portable video equipment, front projectors, and larger flat-panel displays. An LCD projector uses a lamp to shine light through liquid-crystal panels, then through mirrors and lenses to the screen. More info

LCoS - Liquid Crystal on Silicon. Whereas LCDs uses liquid crystals sandwiched between two glass plates, this newer hybrid projection TV technology employs liquid crystals coated on a silicon chip, which results in easier, lower-cost manufacturing and higher-resolution images. More info

letterbox - A wide-screen movie on DVD, laserdisc, or videotape presented in its original theatrical wide-screen width on a standard square 4:3 TV. The film is shown with black bars above and below the picture area to create the wider, theatrical image. Often used to indicate a nonanamorphic DVD.

line-doubler/tripler/multiplier - Technology used in televisions to create a higher-quality picture by increasing the number of lines of resolution displayed; it can be a separate device or a feature built-in TVs, primarily DTVs. A poor-quality line-doubler can actually degrade the image from lower-resolution analog or digital signals.

lumens - The unit of measure for the light output of a projector. Different manufacturers may rate their projectors' light output differently, and these numbers are usually inflated. "Peak lumens" is measured by illuminating an area of about 10 percent of the screen size in the center of the display. This measurement ignores the reduction in brightness at the sides and corners of the screen. See also ANSI lumens

luminance - Portion of a television transmission that controls brightness of the red, green, and blue proportions in a television picture. The standard luminance setting in a picture is 30 percent red, 60 percent green, and 10 percent blue. These numbers are adjusted to produce varying colors, grays, whites, and blacks.