A | B | C | D | E | F | G | H | I | J | K | L | M | N
O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Active-matrix liquid crystal display (AMLCD)
Also known as TFT Display, or Thin Film Transistor Display. An active matrix liquid crystal display is the display industry’s term for the type of flat panel display that is currently the overwhelming choice of notebook computer manufacturers, due to light weight, very good image quality, wide color gamut, and response time. With active matrix displays, each pixel is controlled by a switch-device which actively maintains the pixel state while other pixels are being addressed. This generally makes the screens faster, brighter, and more colorful then passive matrix control of each pixel, while preventing crosstalk from inadvertently changing the state of an unaddressed pixel.

Analog Monitor
An Analog Monitor is a monitor or display that is capable of accepting continuously varying or analog signals from the video source. This allows the monitor to display an infinite range of different colors or grey shades. The majority of CRT monitors are analog, while all flat panel displays are inherently digital in nature.

ANTIALIASING
Any technique used to smooth the jagged edges that are created when diagonal lines are drawn on a digitized image.

Anti-Glare Screen
Anti-Glare Screen refers to a clear panel or filter placed over, or a transparent coating applied to the faceplate of computer monitor to help prevent glare from the sun or other bright light sources from appearing on the screen. These coatings or panels use technologies ranging from a simple etched surface to a quarter wavelength refractive coating wo achieve their purpose in minimizing glare.

Aperture Grille
An Aperture Grille refers to a method of CRT construction employing vertical strips of colored phosphor with a thin screan formed of a grid of tiny metal wires. Electron beams emitted from the electron gun pass through this grid of metal wires and lands on the appropriately-colored phosphor strip, exciting phosphors that produce the on-screen image. An aperture grille construction tends to produce brighter, more saturated colors, but is not as good for text or fine detail.

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B

Brightness
Brightness is the setting of the basic light level intensity in a computer monitor. This is commonly set in conjunction with contrast to improve the quality of the viewable image.

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C

Candela (cd)
The candela is the base unit of measurement of luminous intensity. It is defined as the power emitted by a light source in a particular direction per unit solid angle, weighted by the luminous efficiency function (a mapping of the human eye’s sensitivity to the different wavelengths). A single candela approximates the now-obsolete unit of one candlepower, which was originally defined in England by as the light produced by a pure spermaceti candle weighing one sixth of a pound and burning at a rate of 120 grains per hour.

In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.

Photometry deals with the measurement of visible light as perceived by human eyes. The human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions (photopic vision), the eye is most sensitive to greenish-yellow light at 555 nm. Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which measures the response of the human eye to light is a defined standard, known as the luminosity function. This curve, denoted V(?) or , is based on an average of widely differing experimental data from scientists using different measurement techniques. For instance, the measured responses of the eye to violet light varied by a factor of ten.

Luminous intensity should not be confused with another photometric unit, luminous flux, which is the total perceived power emitted in all directions. Luminous intensity is the perceived power per unit solid angle. Luminous intensity is also not the same as the radiant intensity, the corresponding objective physical quantity used in the measurement science of radiometry.

Candela per Square Meter (cd/m2)
The Candela per Square Meter (also known as a Nit) is the base unit used to measure the luminance of a display. The luminance of a display indicates how of how bright the display’s surface will appear to an eye looking at the surface from a particular angle of view.
Computer displays used in typical room environments typically exhibit luminances ranging from 50 to 300 cd/m2. For a screen to be viewable under direct sunlight, a luminance of at least 800 cd/m2 is generally required.

Cathode-Ray Tube (CRT)
A cathode ray tube (CRT) is a vacuum tube which is used to create images in the form of light emitted from the fluorescent screen. In its simplest form, it contains a source of electrons called an electron gun aimed at a fluorescent screen, with a means to accelerate and deflect the electron beam which is used to create images in the form of light emitted from the fluorescent screen.

Contrast
Contrast is the term used to describe the degree of brightness variation (white through black) in an image.

Contrast Ratio
The contrast ratio is a measurement of a display’s contrast capability, and is defined as the ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing. A high contrast ratio is desired in any display. Unfortunately, due to the various methods of measurement employed, as well as variations in operation and unstated variables, the contrast ratio ratings provided by different manufacturers of display devices are not necessarily comparable to each other, and remarkably different measured values can sometimes produce similar results.

Manufacturers traditionally favor measurement methods that isolate the device from the system environment, since that is a factor not under their control. Consequently their measurement methods simulate an ideal room where the only light seen in the room would come from the display device. With such an ideal room, the contrast ratio of the image would be the same as the device.

Real rooms, however, reflect some of the light back to the displayed image, lowering the contrast ratio seen in the image, so display users must generally take the brightness characteristics of the surroundings into account when designing their systems.

Complicating factors somewhat, the ratio of the luminosity of the brightest and the darkest color the monitor is capable of producing simultaneously at any instant of time is called static contrast ratio, while the ratio of the luminosity of the brightest and the darkest color the display is capable of producing over time is called dynamic contrast ratio.

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D

Dead Pixel
A ‘Dead Pixel’ is the term used to describe a pixel that no longer illuminates. The term is more common on LCD and Plasma display technology, whereas a similar defect on a CRT monitor is simply called a ‘Phosphor Defect’.

Degauss
Degaussing is the method of erasing magnetic charge from a magnetized material. Occasionally, the shadow mask of a color CRT will pick up a magnetic charge, and deform, causing ‘purity’ or discolorations in the video image. The degauss process is achieved by generating a powerful time-varying magnet field that passes through the shadow-mask material and rearranges the magnetic particles in a random order.

Digital Monitor
A Digital Monitor uses a digital video signal rather than an analog video signal to create an image. Unlike an analog monitor, a digital monitor cannot display an infinite range of colors.

Display (Monitor)
Display is the term used to describe the electronic device used to present images and/or text.

Dot Pitch
Dot Pitch is the distance between pixels on a computer display screen. It is generally measured in millimeters.

Dots Per Inch - DPI
DPI (Dots Per Inch) is a measurement of display device’s resolution capability, and indicates how many pixels, or dots, the display device can place in one square inch. The higher the DPI, the sharper the image.

DVI-D
DVI-D stands for "DVI-Digital" and supports digital transfers only.

DVI-I
DVI-I stands for "DVI-Integrated" and supports both digital and analog transfers, so it works with both digital and analog Visual Display Units.

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E

EGA - Enhanced Graphics Adapter
Manufactured by IBM in 1984, the Enhanced Graphics Adaptor (EGA) is a digital video standard that falls between CGA and VGA in terms of color and space resolution. Operating with RGB digital TTL video input signal, EGA offered more color selections (16 distinct colors from a palette of 64) than the earlier CGA standards at video resolutions of up to 640×350 pixels.

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F

Fixed-frequency monitor
Common in older display monitor systems, fixed-frequency monitors are designed to only run at a specific signal from within a limited frequency range.

Flat-Panel display (monitor)
Flatpanel displays (flatpanel monitors) is the term generally used to describe a display device that is not based upon the cathode-ray tube technology. They usually use Liquid-crystal display (LCD) technology, although Plasma and other technologies fit the description as well.

Flat screen Monitor
A Flat screen Monitor generally refers to a CRT monitor whose faceplate is flat, not curved.

Flicker (not to be confused with Yahoo's Flickr)
Flicker describes a flashing, or rapid blinking in an image on a display screen. Flicker generally occurs when the video refresh rate of the display system is too low, but it can also be caused by other video-related problems and in some cases by monitor hardware problems. A flickering screen may cause users to experience eye strain. To avoid flickering, the refresh rate should be at least 72 Hz.

Foot candle
A foot candle is the measurement of amount of light reflected by a surface one foot from a lighted candle. The term is becoming obsolete, and is replaced by SI units of cd/m2 or nits’.

Frame
In the display business, a frame is a single image displayed by the monitor.

Frame rate
The Frame rate, usually measured in Frames Per Second (fps), is frequency at which individual image frames are displayed or projected. Full speed video images generally require a frame rate of 24, 25 and 30 frames per second for optimum performance.

FSTN (Film SuperTwist Nematic)
FSTN is a type of LCD display.

Full-motion video (FMV)
Abbreviated as FMV, Full-Motion Video is the term used to describe video display systems that are capable of displaying full speed video images and sound on a monitor. Depending upon the video format being used, the frames per second can vary, but computers and displays not capable of displaying at least 24fps will create choppy video.

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H

Hercules
Hercules refers to a monochrome graphics standard introduced in the early 1980s and developed by Hercules Computer Technology for IBM compatible computers. The standard defined a resolution of 720 Pixels by 348 pixels on a monochrome monitor.

HGA
Short for Hercules Graphic adapter.

Horizontal scan rate
Horizontal scan rate refers to the speed that each line is drawn horizontally on a display monitor. This is commonly expressed in Kilohertz [KHz].

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I

IRGB (or RGBI)
Red Green Blue Intensity (RGBI) is the technology used to generate a 16-color image on early digital-input computer monitors. 16-colors are created by the addition of an intensity bit to the digital signals controlling the three primary colors, red, blue, and green. The 16 colors created are black, dark gray, light gray blue, light blue, green, light green, cyan, light cyan, red, light red, purple, light purple, yellow, light yellow and white.

Image Burn
When a CRT computer monitor is left for long periods of time with a constant image, the image can seep into screen phosphor, leaving a permanent image. Image Burn occurs more often with older monitors, but it can still occur on new CRT monitors if brightness is set too high. To help prevent this effect, turn off the monitor when not in use, or use a screen saver.

Intensity bit
The intensity bit is a fourth bit of information added to the Red, Green, and Blue bits on early digital CGA monitor that is used to display different intensities of color. For example, the RGBI monitor is capable of displaying 16 different colors because of this bit.

Interlacing
Interlacing refers to one of the two methods commonly used to generate a video image on an electronic display screen (the other being progressive scan). The interlace technique was devised for displaying high-quality full-motion-video images on early CRT televisions at while using minimal bandwidth. Interlacing technique uses two fields to create a frame; one field contains all the odd lines in the image, the other contains all the even lines of the image. The two sets of fields are interleaved to create a full frame every second scan. For a given bandwidth and refresh rate, interlaced video will provide a higher spatial resolution than progressive scan.

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N

Nit
A Nit is another term for one candela per square meter (cd/m2), which is the SI (International System of Units) base unit for measuring luminance. In the display monitor industry, it is used to measure the brightness of the surface area of a CRT monitor, LCD or other display device. A nit is equal to one candela per square meter. The term, Nit, comes from the Latin niter, to shine.

Computer displays typically have luminances of 50 to 300 cd/m2. A luminance of at least 800 cd/m2 is required for a screen to be viewable under direct sunlight.

NTSC
Short for National Television System Committee, NTSC is the American committee responsible for creating technological television and video standards, including refresh rate and color capabilities. NTSC Composite Video is the standard for analog color televisions.

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P

PAL
Short for Phase Alternating Line, PAL is the dominant television standard used across Europe. Pal delivers 625 lines of resolution, interlaced at 50 half-frames per second (25 Frames per second).

Persistence
Display persistence is amount of time it takes for the phosphor in a CRT display to lose all of its charge. The longer the persistence, the less flicker there is. However, long-persistence phosphors exhibit ‘ghosting’ with moving images.

PGA
Short for Professional Graphics Adapter. PGA was an early video standard developed by IBM that supports up to 640x400 resolution.

PPI - Pixels Per Inch (See Dots-per-Inch)
Short for Pixels Per Inch, PPI is the numbers of pixels per inch that comprises a pixel image. Also called ‘dots per inch’, PPI is a measurement of display device’s resolution capability. The more pixels per inch the image contains, the sharper the image will be.

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R

Resolution
The term commonly used to describe the image quality of a printer or monitor. In monitors, the resolution is measured by the number of pixels in a given area, or the number of horizontal pixels X number of vertical pixels.

RGB monitor (Color Monitor)
RGB Monitors are computer monitors that use three distinct video signals (red, green, blue) to generate the colors displayed on the monitor screen.

RGBI (or IRGB)
Red Green Blue Intensity (RGBI) is the technology used to generate a 16-color image on early digital-input computer monitors. 16-colors are created by the addition of an intensity bit to the digital signals controlling the three primary colors, red, blue, and green. The 16 colors created are black, dark gray, light gray blue, light blue, green, light green, cyan, light cyan, red, light red, purple, light purple, yellow, light yellow and white.

RS-170
RS-170 was the original black-and-white television signal standard defined by the EIA (Electronics Industries Association). The RS-170 video standard specifies the timing and signal characteristic of broadcast video in the United States, Japan, and several other markets. It specifies a composite signal with well-defined voltage, sync levels and blanking timings, at a horizontal refresh rate of 15.75-KHz and a 60-Hz vertical interlaced scan frequency.

RS-170 delivers 625 lines of resolution, with the odd and even lines interlaced at 60 half-frames per second (30 Frames per second). The 60-Hz field rate was chosen to give adequate full-motion-video capability while avoiding interference from ac current fields.

RS-170A (NTSC Color Video)
Twenty years after the drafting of RS-170, the EIA video signal standards committee proposed the RS-170A color video standard, which evolved into what is known today as the NTSC composite video signal standard. In this standard, color images are produced on a video display by mixing different intensities of red, green, and blue light which have been encoded onto 1, 2, 3, or 4 wires.

The earliest version of the RS-170A standard was the single-wire composite video format known as the basic NTSC video standard. Based the original RS-170 monochrome video standard, the NTSC color video signal contains intensity, color, and timing information on the same line. The basic intensity and timing information conforms to the RS-170 monochrome standard, while the color information is superimposed on the intensity waveform. Information contained in a ‘color burst’ located in the back porch of each horizontal scan signal is used to decode the color information. This color information is combined with the analog intensity signal to reconstruct the three primary colors needed to generate a colorized image. The encoding scheme was designed such that, with the proper filtering, a RS-170 monochrome monitor will produce an acceptable black and white image when fed an NTSC color video signal.

The two-wire version of the RS-170A color standard is known as "S-Video". In this format, one pair of coax wires carries the Y channel, which contains the combined intensity and timing signals in accordance with the RS-170 monochrome standard. A second wire pair, the ‘chroma’ or C channel, carries a separate color signal which transmits the color information. S-video is usually transmitted over a single cable with a special 4-pin connector on either end.

The four-wire format is known as RGBS for Red, Green, Blue, and Sync. RGBS video is a "component video" format, meaning the various components of information required to reproduce a video display are enclosed by the three separate video signals as well as a separate composite sync signal. In this case the color signal is broken into three separate and equal channels, each carrying high-resolution information. Timing information is provided on a separate wire - the synch channel. Timing information is sometimes also present on the green channel, but more often not. This video format is called RS-170 RGB.

RS-170 RGB
RS-170 RGB refers to RGB signals timed to RS-170 specifications. In RS-170 RGB, the red, green and blue signals are actually three individual monochrome signals representing their respective red, green, and blue colors which conform to the RS-170 video format, and which share one composite sync signal which is (usually) combined with the green signal. Although video intensity information and blank timing intervals are present in the red and blue signals, the composite synchronization pulses typically are not.

Alternatively, a fourth signal containing only the composite synchronization information may be used to drive an external synchronization input of an RGB display.

Some computer graphic displays and some cameras require separate horizontal and vertical drive inputs as well and may require Transistor/Transistor Logic (TTL) voltage pulses (3-5 V).

RS-343
RS-343 is an EIA (Electronics Industries Association) standard for non-broadcast high resolution monochrome video. RS-343 was introduced later than RS-170 and intended as a signal standard for High-definition Closed-Circuit Television. Among other things, it reduced the total composite video signal amplitude to 1.00 Vp-p.

According RS-343, the signal specifications are:

• White: +0.714V
• Black: +0.054V
• Blank: (0V reference)
• Sync: -0.286V

RS-343 specifies a 60 Hz non-interlaced scan with a composite sync signal with a variety of timings that produce a non-interlace (progressive) scan at resolutions ranging from 675 to 1023 lines.

This standard is used by high resolution video cameras used in applications such as: infrared targeting, low-light, night-vision cameras, and other special military display systems.

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S

Screen flicker
Screen flicker describes a flashing, or unsteadiness in an image on a display screen. Flicker most often occurs when the video refresh rate is too low, but it can be due to other video related issues and, in some cases, hardware problems with the monitor. Screen Flicker may cause users to experience eye strain. To avoid flickering, the refresh rate should be at least 72 Hz.

Shadow mask
On standard color CRT monitors, the shadow mask is a perforated metal screen located behind the faceplate of a color CRT to ensure the three colored beams hit the appropriately-colored phosphor dot. All early color televisions and the majority of CRT computer monitors, past and present, use shadow mask technology.

SuperTwisted Nematic
Abbreviated as STN, SuperTwisted Nematic is a type of liquid-crystal-display (LCD) used in portable computers and flat panel displays. STN builds on the twisted nematic (TN) construction method, which twists liquid molecules, causing the LCD display to have a sharper contrast and better viewing angle.

SVGA (Super Video Graphics Array)
Short for Super Video Graphics Array, SVGA is a set of video standards introduced by IBM in 1987 as an extension of the VGA standard. In 1989, Super VGA was adopted and defined by the Video Electronics Standards Association (VESA), an open consortium set up to promote interoperability and define standards.

In the first version, SVGA defined a resolution of 800 × 600 pixels where each pixel could be any of 16 colors selected from a color palette. The SVGA standard was soon expanded to 1024 × 768 8-bit pixels and beyond in the following years.

When used as a resolution specification, the term SVGA mow most commonly refers to the original resolution of 800 × 600 pixels.

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V

VDU
Short for Visual Display Unit, or Video Display Unit, VDU is a term used to describe a device a computer uses to display visual information. Although flat panel displays, monitors and projectors are all examples of a VDU, the term is most commonly used to describe a standard CRT monitor.

VESA - Video Electronics Standard Association
Short for Video Electronics Standard Association, VESA is an international standards organization founded in the late 1980s by a group of monitor and video card manufacturers to define various display standards for computer graphics systems.

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W

WSXGA (Wide SXGA)
Short for Wide SXGA, WSXGA is a resolution that supports 1600 by 900 pixels or 1600 x 1024 pixels.

WUXGA (Wide Ultra Extended Graphics Array)
Short for ‘Wide Ultra Extended Graphics Array’, WUXGA has a resolution of 1920 by 1200 pixels.

WXGA
Short for Wide XGA, WXGA is a video resolution that supports a maximum resolution of 1366 by 768 pixels.