A/V technology and technical terms explained

calibration - In televisions, the process of adjusting a picture to comply with standards used in DVD and HDTV production.

CEA - Consumer Electronics Association, the principal industry association for companies that manufacture consumer electronics.

CEDIA - Custom Electronics Design and Installation Association, the industry group for installers of home-theater, multizone audio, phone, security, lighting, and other home equipment.

chrominance - Technical name for the TV signal that carries the color information (red, green, and blue) needed to produce a color picture; often called chroma.

chrominance-to-luminance delay - Video artifact caused by the color signal lagging the brightness signal; appears as color smearing on the left edges of some onscreen objects; easiest to see with a test pattern that has a colored vertical stripe running down the middle of a white field.

color decoder - Component in all televisions that translates color-signal information from the source for display on the TV. ATSC and NTSC require two separate decoder matrices. Practically speaking, many color decoders accentuate red to compensate for a blue color temperature, a phenomenon known as red push.

color temperature - Sometimes called white balance and expressed in degrees kelvin or just Kelvins, this is the color of gray at different levels from black to white. Since color information overlays the black-and-white information in a TV signal, color temperature affects the entire range of color. The National Television Standards Committee (NTSC) standard is 6,500K, but typically manufacturers ship their TVs with color temperatures ranging from about 7,000K to 12,000K, on the blue side of the color spectrum, to make sets as bright as possible to stand out on a brightly lit showroom sales floor. Some sets have a selectable color temperature.

color shift - This is an anomaly which affects color vibrancy when a TV is viewed away from the center of a screen. Color shift is closely related to a display's viewing angle and can result in washed-out hues.

comb filter - Component in all televisions that separates the chrominance and luminance from one another in composite-video connections. Good comb filtering enhances fine detail, cleans up image outlines, and eliminates most extraneous colors. Comb filters do not affect S-Video, component-video or digital-video connections.

component video - The elements that make up a video signal, consisting of luminance and two separate chrominance signals, expressed either as Y R-Y B-Y or Y Pb Pr.

composite video - Analog video signal that includes vertical and horizontal synchronizing information. Since both luminance and chrominance signals are encoded together, only a single connection wire or jack is needed.

compression - Method of electronically reducing the number of bits required to store or transmit data. The method adopted for DTV is called MPEG-2. Four full-range channels of programming and data can be compressed into the same space required by a single analog channel.

contrast ratio - Difference between the brightest whites and the darkest blacks a display can show. The higher the contrast ratio, the greater the ability to show subtle color details and tolerate ambient room light (for example). Most contrast-ratio specs reported by manufacturers are inflated.

CPTWG - Copy Protection Technical Working Group, a committee formed by consumer electronics and computer industry companies to recommend DVD and DTV copy-protection protocols.

CRT - cathode-ray tube, the original and still the most common display technology for televisions. Invented in 1897 by German physicist Karl Ferdinand Braun, the tube uses an electron beam to scan lines on the screen. It does not have an exact resolution as a fixed-pixel display does.