Glossary

Vocabulary that holds the terms for the vocabulary.

c
Cathode Ray Tube (CRT)search for term

Analogue display device that generates an image on a layer of phosphors that are driven by an electron gun.

Cb, Crsearch for term

Refers to the color component video signals B-Y, R-Y respectively optimized for digital purposes or transmission. Sometimes loosely used to refer to B-Y (Pb) and R-Y (Pr) in any context.

Chromasearch for term

The characteristics of color information, independent of luminance intensity. Hue and saturation are qualities of chroma. Black, gray, and white objects do not have chroma characteristics.

Chroma Levelsearch for term

In video, a measure of color saturation.

Chroma Phasesearch for term

In video, a measure of color hue, usually adjustable with the tint control on a TV set.

Chroma-Differential Gainsearch for term

In video, a measure of how color saturation varies with scene brightness.

Chroma-Differential Phasesearch for term

In video, a measure of how color hue varies with scene brightness.

Chromatic Aberrationsearch for term

An optical defect of a lens which causes different colors or wave lengths of light to be focused at different distances from the lens. It is seen as color fringes or halos along edges and around every point in the image.

Chromaticitysearch for term

The color quality of light that is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.

Chrominancesearch for term

The amount of color; or the saturation of color, in a picture. Does not refer to brightness.

Color wheelsearch for term

Central to DLP™ technology's unique color filtration process, the color wheel is a small spinning disk composed of red, green, and blue filters which rotates at speeds exceeding 120 revolutions per second. The DMD (Digital Micromirror Device) briefly creates an image for each color. The viewer's eye combines these images to form a complete picture.

Colour Noisesearch for term

The irregular, grainy characteristic that appears in large color areas on all video pictures. The level of noise will vary, depending on the quality of the TV set, the quality of the playback device, and the quality of the source material.

Colour Temperaturesearch for term

A method of measuring the "whiteness" of a light source. Metal halide lamps have very high temperatures compared to halogen or incandescent lights.

Colour Wheelsearch for term

Central to DLP™ technology's unique colour filtration process, the colour wheel is a small spinning disk composed of red, green, and blue filters which rotates at speeds exceeding 120 revolutions per second. The DMD (Digital Micromirror Device) briefly creates an image for each colour. The viewer's eye combines these images to form a complete picture.

Comb Filter - Video:search for term

A circuit that separates chrominance and luminance signals in a television set or laser-video player to control interference. In many sets, it is digitally implemented. It is superior to the simple "notch" filters found in older and cheaper sets.

Comb Filteringsearch for term

A hollow coloration that, once recognized, is unmistakable. Caused by a regularly spaced series of frequency-response peaks and dips, most often due to interference between two identical signals spaced in time. If that time difference is continually changed, the comb-filter peaks and dips move accordingly, giving rise to the familiar "phasing," "flanging," or "jet plane" effect used in modern rock music.

Component Videosearch for term

A signal that's recorded or transmitted in its separate components. Typically refers to Y/Pb/Pr, which consists of three 75-ohm channels: one for luminance (luma) information, and two for color (chroma). Compared with an S-video signal, a Y/Pb/Pr signal carries more color detail. HDTV, DVD, and DBS are component video sources, though most DBS material is transcoded to component from composite signals.

Composite Videosearch for term

A signal that contains both chrominance and luminance on the same 75-ohm cable. Used in nearly all consumer video devices. Chrominance is carried in a 3.58-mHz sideband and filtered out by the TV's notch or comb filter. Poor filtering can result in dot crawl, hanging dots, or other image artifacts. NTSC, PAL, and SECAM are all examples of composite video systems.

Compressed Resolutionsearch for term

Most projectors automatically accept images that are of greater resolution than the native (true) resolution of the projector. The resulting image is scaled to fit the native resolution of the projector using a variety of scaling algorithms. Not all projectors use the same compression algorithms; therefore, the quality of compression can vary. The nature of compression in a digital device means that some image content is lost.

Compressed SVGAsearch for term

Unlike CRT based monitors, LCD and DLP projectors only have one "true" resolution. Most projectors out there are VGA (640x480) resolution. To project an 800x600 image to a VGA projector, the original 800x600 signal must be compressed down to VGA. This is done by interpolating the data, and trying to best display all the information with only two thirds of the pixels (307,000 vs 480,000). The resulting image gives you the SVGA page size, but some sacrifice of image quality. For the vast majority of people with SVGA laptops or desktops, they will have more satisfying results, outputting VGA to a VGA projector.

Compressed SXGAsearch for term

Found on XGA projectors, compressed SXGA handling allows these projectors to handle up to 1280x1024 SXGA resolution. Most owners of XGA projectors that use the compressed SXGA are workstation users (SUN, SGI, IBM, HP...) The typical uses f or these workstations are medical, life sciences, engineering and so on.

Compressed XGAsearch for term

Found on SVGA projectors, compressed XGA handling allows these projectors to handle 1024x768 XGA resolution. How good the compressed XGA is on a given model is a key factor in the decision process for most people choosing an SVGA projector. This is true as the market shifts from SVGA laptops to those with XGA screens.

Contrast ratiosearch for term

Relative difference between the brightest and darkest parts of an image. It is calculated by dividing the peak white level by the light level at the dark park of the picture. Measurements are taken by displaying a 100% Window pattern and measuring the peak white and an area of black near the white rectangle. A contrast control adjusts the peak white level of a display device.

Convergencesearch for term

The correct aiming of the three electron beams in a direct viewed picture tube or three separate pictures from tubes in a projection TV (for red, blue, and green) to be together at all times. Without proper convergence, objects on the screen will have colored halos around them, white lines will seem to have a red, green, or blue line next to them, and resolution will be poorer. The most common reason for misconvergence is the coils attached to the neck of the picture tube not in the proper position which usually takes a time consuming trial and error process to correct. Often perfect convergence cannot be achieved over the entire screen so a compromise where the errors are minimized but not completely eliminated must be accepted. It may be noted that a convergence error of one fifth of one percent means that one of the electron beams is off by a scan line causing a halving of the resolution at that spot on the screen. Also "convergence" refers to the bringing together and integrating of two or more systems or technologies so that components can be shared. An example is the development and manufacturing of video monitors suitable for television, movies, entertainment, and also computers and data display.

Convergence (Dynamic)search for term

This is the fine convergence adjustment and is carried out by either internal adjustment controls or in the case of the newer RPTV sets it is done digitally thru software built into the set.

Convergence (Static)search for term

This term is used to describe how each of the three images intersects onto the screen of an RPTV. This "convergence" of image must take place at the same point on the screen for each color to perform its "additive" function. The static adjustment is carried out by utilizing a crosshatch pattern and centering magnets on the CRTs (course adjustment).

Cross Colorsearch for term

Rainbow swirls amongst or swamping out pinstripes and other fine detail, caused by small amounts of luminance signal left behind in the signal going into the color circuits. This situation is the result of imperfect Y/C separation by the comb filter

Cross Luminancesearch for term

Crawling or hanging dots where color patches meet, or silk screen effects, caused by small amounts of color signal going into the luminance circuits. This situation is the result of imperfect Y/C separation by the comb filter

CRTsearch for term

See Cathode Ray Tube.