Skip to main content
Christie Digital Christie Digital

Glossary of AV terms and definitions

Click on any letter to help grow your AV knowledge.


See: DLP.


A display specification that is capable of displaying 2048 x 1080 resolution, or approximately 2.2 million pixels.


The sequence of single, alternating frames where each successive frame carries the image meant for either the right or left eye. The image is viewed by each eye at 60 frames per second (FPS). Each eye sees the full resolution of the image. This type of 3D is also known as frame alternative or page flip.


See: DLP.


A display specification that is capable of displaying 4096 x 2160 resolution, or approximately 8.85 million pixels.


Developed primarily for 3D applications, 6P laser projection uses two sets of RGB lasers: one for the left eye, and one with slightly different wavelengths for the right eye. "6P" refers to these six primary colors of laser light, with three for each eye. 3D glasses filter the wavelengths, directing the light to the correct eye. Unlike traditional 3D, Christie’s 6P laser projection presents images simultaneously to the right and left eye. This eliminates the fatigue, headaches and nausea some viewers experience with traditional 3D projection, where our brains have to correct for the temporal offset created by images flashing sequentially to the right and left eye. The benefits of 6P include higher brightness, a wider range of color and detail, and a better viewing experience.


See: RF Jack.


Developed specifically for the simulation market, AccuFrame nullifies image artifacts (such as smearing or double-image perception) in high speed simulation. A fully-adjustable electronic solution, AccuFrame supports various frame rates and environments, delivering accurate frame display. AccuFrame enables the removal of any perceived "double imaging" of content due to image frame perception in the eye.

Active line time

The time, inside one horizontal scan line, it takes to generate video.

Additive color model

A projector model that uses red, green and blue light as the additive primary colors to produce the other colors. Combining one of the additive primary colors with another in equal amounts produces the additive secondary colors: cyan, magenta and yellow. Combining all three additive primary colors in equal intensities produces white.

Alternative content

Non-cinema program material such as concerts, plays, sporting events, and potentially corporate training or conferences, presented in theaters.

Ambient light rejection

The ability of a screen to reflect ambient light in a direction away from the line of best viewing.

Analog video

The nondigital video output format of most computers and videotape machines. Analog video can generate a large number of colors.


Having or requiring a linear distortion, generally horizontally. Anamorphic lenses can restore a ‘scope’ (CinemaScope) or flat-format film frame to the correct widescreen appearance by increasing its horizontal proportion.


The American National Standards Institute is the organization that denotes the measurement standard for lamp brightness.

ANSI lumens

Industry standard measurement for determining overall light-output, including the edges and corners of the screen. Differs from center lumens, which takes the light output measurement from the middle of the lamp, often resulting in a higher measurement.


Content management system enabling automatic color and brightness management over multiple tiled screens.

Aspect ratio

The ratio of the width of an image to its height, such as the 4:3 aspect ratio common in video output. Aspect ratio can also be expressed as a decimal number, such as 1.77, 1.85 or 2.39. The larger the ratio or decimal, the wider and "less square" the image.

Auto source

The ability of the projector to automatically recognize and synchronize to the horizontal and vertical scan frequencies of an input signal for proper display.

Automation system

A system used in a theater projection booth that responds to cues, commands or relay switches and then controls various elements of presentation, such as:

  • picture format and corresponding lens (flat or scope)
  • sound format and corresponding cinema processor settings
  • curtain movement and position
  • lighting level in the auditorium
  • non-sync play and fade in/out
  • digital cinema projector

Average Picture Level (APL)

The average level of the picture signal during active scanning time integrated over a frame period; defined as a percentage of the range between blanking and reference white level.


The power source for a projector’s lamp.


The frequency range of a projector’s video amplifier.

Baud rate

The speed (bits-per-second) at which serial communications travel from their origin.

Blanking time

The time inside one horizontal scan line during which video is not generated. The blanking time of the input signal must be equal to, or greater than, the retrace time of the projector.


In projection, brightness describes the amount of light that is reflected off of the projection surface, such as a screen. Brightness is measured in footlamberts or candelas per square meter.

Candela or candle

Unit of measure for measuring intensity of light. Written as: x cd.


A collection of measurements stored by the projector for a given input source, including frequencies, pulse width, polarity, syncs, channel number and location, user-adjustable display settings, etc. Channels are used to switch between a variety of setups quickly, automatically recalling previously-defined display parameters.

Channel list

A list/menu of previously-defined channels available in a projector’s memory.

Channel number

A number that uniquely identifies a specific channel retained in a projector’s memory. Christie’s 3-chip DLP® projectors can retain up to 99 channels.


The signal representing the color information (hue and saturation) when the image is represented as separate chrominance and luminance. Same as "chroma."

Coaxial connections

See: RF Jack.

Color gamut

The range of colors allowed in a specific system, as defined within a triangular area located on the International Commission on Illumination (CIE) color locus diagram. The triangular area’s corners are the three primary colors defined in the system. Also known as color space.

Color shift

A change in the tint of a white field across an image.

Color temperature

The coloration (reddish, white, bluish, greenish, etc.) of white in an image, measured using the Kelvin (degrees K) temperature scale. Higher temperatures produce more light.

Component video

See: YPbPr.

Composite video

The output of videotape players and some computers, characterized by synchronization, luminance and color signals combined on one output cable.

Contrast (ratio)

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 a desired aspect.


The alignment of the red, green, and blue elements of a projected image so that they appear as a single element.


Cathode ray tube is a vacuum tube in which a beam of electrons is projected on a fluorescent screen to produce a luminous spot. CRTs are used in traditional television sets, computer monitors and some medical devices.

Curved screen

A projection screen that is slightly concave for improved screen gain. Curved screens usually have screen gains that are greater than one but viewing angles much less than 180°.


Display Data Channel standards - part of the Video Electronics Standards Association standards - allows communication between PCs and monitors.


A "direct digital interface" signal can be supplied to a projector using an optional digital input module. For example, you can input an SMPTE- 259M signal using a Serial Digital Input Module or input an SMPTE-272M signal from a Digital HDTV Serial Input Module.


A device that typically converts NTSC 3.58, NTSC 4.4, PAL, PAL-N, PAL-M, or SECAM to RGB video.


The sharpness of a display from a video source.

Diffused screen

A type of rear-projection screen that spreads the light striking it. Screen gain is less than one, but audience viewing angles are increased.

Digital interpolation

Also known as digital scaling, it is the process of averaging pixel information when scaling (resizing) an image up or down. When reducing the size of an image, adjacent pixels are averaged to create fewer pixels. When increasing the size of an image, additional pixels are created by averaging together adjacent pixels in the original smaller image.

Digital video

A video output that provides a higher-quality picture compared to analog ideo output.

Display setting

An adjustment that affects the display of an image. Display settings include contrast, brightness, tint, blanking, size, offsets and others.


A method used for creating grayscale in 1-chip projections. Dithering can be either spatial or temporal.

DLP® (Digital Light Processing)

DLP® is a proprietary technology developed by Texas Instruments. The DLP® chip contains a rectangular array of up to 2 million hingemounted microscopic mirrors. Each of these micromirrors measures less than one-fifth the width of a human hair.

A DLP® chip’s micromirrors tilt either toward the light source in a DLP® projection system (ON) or away from it (OFF). This creates a light or dark pixel on the projection surface.

The white light generated by the lamp in a DLP® projection system passes through a color filter as it travels to the surface of the DLP® chip. This filters the light into a minimum of red, green, and blue, from which a single-chip DLP® (1DLP) projection system can create at least 16.7 million colors.

With BrilliantColor® Technology, additional colors are added including cyan, magenta and yellow to expand the color pallet for even more vibrant color performance. Some DLP® projectors offer solid-state illumination that replaces the traditional white lamp. As a result, the light source emits the necessary colors eliminating the color filter. In some DLP® systems, a 3-chip (3DLP) architecture is used, particularly for high-brightness projectors required for large venues such as concerts and movie theaters. These systems are capable of producing up to 35 trillion colors.

The on and off states of each micromirror are coordinated with these basic building blocks of color. For example, a mirror responsible for projecting a purple pixel will only reflect red and blue light to the projection surface; those colors are then blended to see the intended hue in a projected image.


Digital Micromirror Devices® - a display device chip in a DLP® projector, that is the core device of Texas Instruments’ DLP® technology.

DMX512 communication protocol

Enables projectors to be controlled by the same system used to control stage lights and effects for a live event.

Dot clock

The maximum frequency of the pixel clock. Also known as pixel clock rate. This rate refers to the total number of pixels per second a display can write to the screen.


Dark Video Enhancement - a technique used to create sharper grayscale beside black.


The Enhanced Extended Display Identification Data standard, established by the Video Electronics Standards Association (VESA) lets the display card in a controlling device, such as a PC, detect properties (e.g. resolution). The PC, in turn, can then produce output in a matching format to fill the display. Some sources used with the projector are VESA E-EDID reported.


A very rapid variation in image brightness caused by a frame rate that is too slow. See: Interlace and Lamp Flicker.


Full on/full off.


Unit of measurement that represents the intensity of visible light per square foot.


Unit of measurement (fL) that represents the luminance (brightness) that results from one footcandle of illumination falling on a perfectly diffuse surface.

Frame doubled

The alternating sequence of the image is shown to either the right or left eye, but each frame contains a subframe of the same image. These images are seen twice by each eye at 30 frames per second (FPS) (compared to 60 FPS) providing a 3D image that is viewed at 96-120Hz. This method improves content that might have flicker issues due to low refresh rates.

Frame packed

The frame packed method has a single frame of Full HD 3D content containing both frames for each eye. To maintain full 1080p resolution, the subframes for each eye are stacked vertically one on top of the other. The specification for this format states tha tthe two vertically stacked subframes must also be separated by a buffer zone (or active blanking zone) that consists of a blank 1920 x 45 pixel strip between the two subframes. As a result, a single frame has a resolution of 1920 x 2205. All HDMI 1.4 compliant displays (Blu-ray) need to be able to handle this frame packing format.

Frame rate

The frequency at which complete images are generated and seen by each eye. For non-interlaced signals, the frame rate is identical to the vertical frequency. For interlaced signals, the frame rate (also known as field rate) is one half of vertical frequency.

Frame sequential - native 3D

The sequence of single, alternating frames where each successive frame carries the image meant for either the right or left eye. The image is viewed by each eye at 60 frames per second. Each eye sees the full resolution of the image. This type of 3D is also known as frame alternative or page flip.

Frame tripled - triple flash

The alternating sequence of the image is shown to either the right or left eye, but each frame contains two subframes of the same image. These images are viewed by each eye at 24 FPS, which creates a sharper, more detailed and true-to-life 3D display.


See: RF Jack.

Gain or screen gain

The ability of a screen to direct incident light to an audience. A flat matte white wall has a gain of approximately one. Screens with gain less than one attenuate incident light. Screens with gain more than one direct more incident light to the audience, but have a narrow viewing angle. For example: An image reflecting off a 10 gain screen appears 10 times brighter than it would if reflected off a matte white wall. Curved screens usually have larger gain than flat screens.


General Purpose Input Output, used for remote control of a limited number of programmable functions by direct signal or dry-contact connection.


High-definition (HD) is a display specification that is capable of displaying 1920 x 1080 resolution, or approximately 2 million pixels.


High-definition television (1035, 1080 and 1125 lines interlace, and 720 and 1080 line progressive formats with a 16:9 (i.e. 1.77) aspect ratio.

High frame rates or HFR

HFR movies record and play visuals at twice or more the rate of that seen in today’s cinemas, meaning less flicker, motion blur and stuttered movement. The improvements to 3D movies will be particularly dramatic, creating ultra-realistic movie-going experiences, and resolving some of the issues that have been problematic for the medium.

Horizontal frequency

The frequency at which scan lines are generated, which varies amongst sources. Also called horizontal scan rate or line rate.

Horizontal offset

The difference between the center of the projected image and the center of the projector lens. For clarity, offset is often expressed as the maximum amount of the image that can be projected to one side of the lens center without degrading the image quality. Horizontal offset ranges can be affected by the type of lens in use, and whether or not the image is offset vertically at the same time.

Horizontal scan rates

See: Horizontal frequency.

Hot spot

A circular area of a screen where the image appears brighter than elsewhere on the screen. A hot spot appears along the line of sight and moves with the line of sight. High-gain screens and rear screens designed for slide or movie projection usually have a hot spot.


A physical connection route for a source signal, described by a two-digit number representing 1) its switcher/projector location and 2) its slot in the switcher/projector.

Input signal

Information sent from a source device to the projector.

Integrated Media Block (IMB)

The media block is an important part of a digital cinema system. It decrypts and decodes the feature-film (Hollywood) content and delivers it to the projector in a useable format. Media blocks also manage the Key Delivery Messages (KDMs) - the decryption keys used to unlock the feature-film content at show time. The Christie integrated media block (IMB) is a concise, allin- one solution.


A device, such as the Serial Digital Input Module, that accepts an input signal for the projector to display.


A method used by videotape players and some computers to double the vertical resolution without increasing the horizontal line rate. If the resulting frame/field rate is too low, the image may flicker depending on the image content.

There are no definitions for this letter.


A distortion of the image that occurs when the top and bottom borders of the image are an unequal length. Side borders both slant in or out, producing a keyhole-shaped image that’s caused when the screen and lens surface are not parallel.


Liquid Crystal Display (LCD) projectors usually contain three separate LCD glass panels, one each for the red, green and blue components of the video signal that’s fed into the projector. As light passes through the LCD panels, individual pixels can be opened to allow light to pass or closed to block the light, as if each pixel were fitted with a venetian blind. This activity modulates the light and produces the image that is projected onto the screen.


Liquid crystal light valve.


Liquid crystal on silicone.

Line rate

See: Horizontal frequency.


The reproduction of the horizontal and vertical size of characters and/or shapes over the entire screen.


A Christie software feature where samples of output light from a projector trigger automatic adjustments in the lamp ballast power in order to maintain a constant light output over time. Also known as brightness tracking.


The unit of measure for the amount of visible light emitted by a light source.

Different manufacturers may rate their projectors’ light output differently, and these numbers are usually inflated. "Center 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: ANSI lumens.


The signal representing the measurable intensity (comparable to brightness) of an electronic image when the image is represented as separate chrominance and luminance. Luminance also expresses the light intensity of a diffuse source as a function of its area measured in lumens or candles per square foot (one lumen per square foot = one footlambert). SMPTE RP 98 calls for a luminance of 12 to 22 footlamberts for theater screens. See: Footlambert.


The amount of visible light per square meter incident on a surface. One lux = one lumen/square meter = 0.093 foot-candles.


Microelectrical Mechanical Systems (MEMS) are a method for creating extremely-small scale mechanical devices, such as the hinges used on DMDs.


A Micro Lens Array (MLA) is a group of tiny lenses that are used in some digital projectors to focus light to the active areas of an LCD. They increase the light that passes through each pixel element, thereby reducing the screen door effect.


Minimum Processing Latency (MPL) is a feature that provides less than a single frame of propagation delay between the projector input and the display.

MTTR or mean time to repair

The arithmetic mean (average) time to repair a failed device. MTBF or mean time between failures The arithmetic mean (average) time between failures of a system.

Native resolution

The resolution at which a projector is designed to display images. Image signals higher or lower than a specified native resolution must be converted to be displayed accurately. For example, a projector with a native resolution of HD (1920 x 1080) can display HD content without scaling, but other content (e.g. 4:3) must be scaled to fit the screen.


National Television Standards Committee (NTSC) video is an output format of some videotape and disc players. There are two types of NTSC video: NTSC 3.58 and NTSC 4.43. NTSC 3.58 is used primarily in North America and Japan. NTSC 4.43 is less commonly used.

Optical screen

A type of rear-projection screen that redirects light through the screen to increase image brightness in front of the screen. Screen gain is usually greater than one but audience viewing angles are reduced.


Phase Alternating Line (PAL) video is a 50Hz standard with 768 x 576 resolution. PAL is found on some videotape and disc players (used primarily in Europe, China and some South American and African countries).

Passive stereoscopic viewing

With a passive stereoscopic display the image is split into the left or right eye through polarization filters used both at the projector and as part of lightweight glasses that the user wears.


Plasma Display Panel (PDP) is a type of flat panel display common to large televisions 30 inches or larger. The technology uses small cells containing electrically-charged ionized gases.


A distortion of the image shape characterized by concave edges.


The smallest controllable element of a picture represented on the screen.

Pixel pitch

The distance from the center of an LED pixel to the center of the next LED pixel measured in millimeters.

Presentation level

The projector is at presentation level when an image from a source is displayed without the presence of a slidebar, menu, pull-down list or error message.

Projector-to-screen distance

See: Throw distance.


The type of code format called "A" or "B" used by the remote keypad(s). Protocol "A" is the default protocol set at manufacture. By using two different keypad protocols, adjacent projectors can be controlled independently with their remote infrared (IR) keypads.

Pull-down list

A selectable menu item that unfolds into a list of additional options.

Pulldown, 3:2

A frame sequence used to map 24-frames-per-second (FPS) film to 30-FPS video (or 24/1.001 to 30/1.001 FPS) in which every second film frame is represented by three video fields instead of two, the third frame being a repeat of the second. This technique leads to a set of 10 video fields for each four film frames.


Pulse Width Modulation is a method that distributes on and off light durations in a frame to create grayscale.

There are no definitions for this letter.

Rear screen

A translucent panel that allows incident light from a projector to pass through when projected on from one side so the image can be viewed by an audience on the other side.


The ability to manipulate the physical size, placement and/or aspect ratio of an image using software commands.

Resolution (lens)

The maximum number of alternate white and black horizontal lines that can be distinguished on a screen when a photographic target is placed between the lens and a light source and illuminated by that source.

Resolution (projector)

The maximum number of pixels that the projector can display horizontally and vertically across an image, such as 1024 x 768 (called XGA).

RF jack

Radio frequency jack (RF jack) is an audio/video connection commonly used to bring signals from antennae, cable systems and satellite dishes to components with some type of tuner, such as cable boxes, cable modems, HDTV set-top boxes, VCRs, satellite receivers, TVs, etc. An RF jack can carry video and stereo-audio information simultaneously. When used to connect two components, such as a VCR and a TV, RF provides the lowest video quality of any connection. RF cable connectors usually screw or push onto the jack. Also called F-type, 75-ohm, or coaxial connections.

RGB video

The video output (analog or digital) of most computers. Analog RGB video can have three, four or five wires - one each for red, green, and blue, and either none, one or two for sync. For threewire RGB, the green wire usually provides sync. See: TTL video.

Rise time

The time required by the video amplifier of the projector to increase its output from 10 to 90 percent of the maximum value.


A common, asynchronous data transmission standard recommended by the Electronics Industries Association (EIA). Also called serial communication.


A less common, asynchronous data transmission standard in which balanced differential voltage is specified. RS-422 is especially suited to long distances.

Scan frequency

The horizontal or vertical frequency at which images are generated. Also known as scan rate or refresh rate.

Scan line

One horizontal line on the display.

Scan rate

See: Scan frequency.

Screen door effect

Image distortion that looks like the picture is seen through a screen door. The picture has thin vertical and horizontal black lines running through it.


Sequential Couleur á Mémoire (SECAM) is a video output format of some videotape and disc players (used primarily in France). SECAM signals are similar in resolution and frequency to PAL signals. The primary difference between the two standards is in the way color information is encoded.

Serial communication

See: RS-232.

Side-by-side content

Typically used for broadcast, side-by-side content presents two images beside each other. A single frame contains a horizontally-scaled combination of the left and right eye. Each image is horizontally scaled at half 1080 or 720 resolution. The image is then extracted as frame sequential left and right, but must then be rescaled to full HD resolution. This method is ideal for 3DTV broadcast - 1080i.


The device, such as a computer or VCR, connected to the projector for display. A source may have numerous corresponding channels defined and recognized by the projector. See: Input.

Spatial dithering

The pixels next to each other are given different luminance value to emulate a color.


The creation of a 3D or stereoscopic display is based on the principle that a person’s eyes see two different viewpoints. These two distinct viewpoints are then projected onto a screen so that each eye sees the proper perspective - the left eye sees only the left-eye viewpoint, and the right eye sees only the right-eye viewpoint. The brain then reads both viewpoints simultaneously to produce a single image with the depth necessary to make it appear three dimensional.

There are two ways to present 3D content - active stereoscopic or passive stereoscopic displays.


The output from certain videotape players and video equipment. S-Video separates sync and luminance from color information, typically producing a higher-quality display than composite video.


A signal selector that can be connected to a projector for the purpose of adding more sources.


Super Extended Graphics Array (SXGA) is a display specification that is capable of displaying 1280 x 1024 resolution, or approximately 1.3 million pixels.


Super Extended Graphics Array (SXGA+) is a display specification that is capable of displaying 1400 x 1050 resolution, or approximately 1.5 million pixels.


This term refers to the part of the video signal that is used to stabilize the picture.

  • Composite sync: the horizontal and vertical components are together on one cable
  • Sync-on-green: the sync is part of the green video
  • Separate sync or "H.SYNC and V.SYNC": the horizontal and vertical components of the sync are on two separate cables

Sync width

The duration of each sync pulse generated by a computer. The sync width is part of the blanking time.


Touch control panel.

Throw distance

The distance between the front feet of the projector and the screen. Also called "Projector-to-Screen Distance." Always use the correct Christie throw distance formula to calculate the proper throw distance (±5%) required for your lens.

Throw ratio

Throw ratio = throw distance / screen width. Typically used to differentiate lenses.


Balance of red-to-green necessary for realistic representation of NTSC signals.

Top/bottom content

Also known as top/down, over/under and above/below, this method of displaying 3D uses two images that are presented together, one on top of the other. A single frame contains a vertically-scaled combination of the left and right eye together. The image is vertically scaled at half 1080 or 720 resolution and then extracted as frame sequential left and right, but must then be rescaled to full resolution. Typically 3D gaming consoles use this type of 3D.


Ultra Extended Graphics Array (UXGA) is a display specification that is capable of displaying 1600 x 1200 resolution, or approximately 1.9 million pixels.

Variable scan

The ability of a projector to synchronize to inputs with frequencies within a specified range.

Vertical frequency

The frequency at which images are generated. Vertical frequencies vary among sources. Also called vertical scan rate.

Vertical offset

The difference between the center of the projected image and the center of the projector lens. For clarity, offset is often expressed as the maximum amount of the image that can be projected above or below the lens center without degrading the image quality. Vertical offset ranges depend on the type of lens in use, and whether or not the image is offset horizontally at the same time.

Vertical scan rate

See: Vertical frequency.

Video decoder

An optional device that converts NTSC 3.58, NTSC 4.4, PAL, PAL-N, PAL-M or SECAM to RGB video.

Video standard

A specific type of video signal, such as NTSC, PAL, SECAM that allows a projector to automatically recognize and interpret the incoming standard and display accordingly.

Viewing angle

Screens do not reflect equally in all directions. Most light is reflected in a conical volume centered around the line of best viewing. Maximum brightness is perceived if you are within the viewing cone defined by the horizontal and vertical viewing angles.

White balance

The color temperature of white used by the projector.

White field

The area of an image that is white only. For example, a full white field is an image that is white everywhere. A 10 percent white field is a white area (usually rectangular) that occupies 10 percent of the image; the remaining 90 percent is black.


Widescreen Ultra Extended Graphics Array (WUXGA) is a display specification that is capable of displaying 1920 x 1200 resolution, or approximately 2.3 million pixels.


Widescreen Extended Graphics Array (WXGA) is a display specification that is capable of displaying 1280 x 800 resolution, or approximately 1 million pixels.


Extended Graphics Array (XGA) is a display specification that is capable of displaying 1024 x 768 resolution, or approximately 0.79 million pixels. It was introduced by IBM in 1990 and designed to replace the older 8514/A video standard. XGA allows monitors to be non-interlaced.


A high-end analog component video signal. Sometimes called YUV, Component, or Y, R-Y, B-Y, the YPbPr signal bypasses the video decoder in this projector.


See: YPbPr.


The adjustment of image size using a zoom lens.