Video projector in the context of Plug and Display

A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen.

The most common type of projector used today is called a video projector. Video projectors are digital replacements for earlier types of projectors such as slide projectors and overhead projectors. These earlier types of projectors were mostly replaced with digital video projectors throughout the 1990s and early 2000s, but old analog projectors are still used at some places. The newest types of projectors are handheld projectors that use lasers or LEDs to project images.

Digital cinema is the digital technology used within the film industry to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the Internet or dedicated satellite links, or by sending hard drives or optical discs such as Blu-ray discs, then projected using a digital video projector instead of a film projector.

Typically, digital movies are shot using digital movie cameras or in animation transferred from a file and are edited using a non-linear editing system (NLE). The NLE is often a video editing application installed in one or more computers that may be networked to access the original footage from a remote server, share or gain access to computing resources for rendering the final video, and allow several editors to work on the same timeline or project.

Multi-monitor, also called multi-display and multi-head, is the use of multiple physical display devices, such as monitors, televisions, and projectors, in order to increase the area available for computer programs running on a single computer system. Research studies show that, depending on the type of work, multi-head may increase the productivity by between 50 and 70 percent.

A movie projector (or film projector) is an opto-mechanical device for displaying motion picture film by projecting it onto a screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras. Modern movie projectors are specially built video projectors (see also digital cinema).

Many projectors are specific to a particular film gauge and not all movie projectors are film projectors since the use of film is required.

In photography and optics, vignetting (/vɪnˈjɛtɪŋ/ vin-YET-ing) is a reduction of an image's brightness or saturation toward the periphery compared to the image center. The word vignette, from the same root as vine, originally referred to a decorative border in a book. Later, the word came to be used for a photographic portrait that is clear at the center and fades off toward the edges. A similar effect is visible in photographs of projected images or videos off a projection screen, resulting in a so-called "hotspot" effect.

Vignetting is often an unintended and undesired effect caused by camera settings or lens limitations. However, it is sometimes deliberately introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens that is known to produce vignetting to obtain the effect, or it may be introduced with the use of special filters or post-processing procedures.

A movie camera (also known as a film camera and cine-camera) is a type of photographic camera that rapidly takes a sequence of photographs, either onto film stock or an image sensor, in order to produce a moving image to display on a screen. In contrast to the still camera, which captures a single image at a time, the movie camera takes a series of images by way of an intermittent mechanism or by electronic means; each image is a frame of film or video. The frames are projected through a movie projector or a video projector at a specific frame rate (number of frames per second) to show the moving picture. When projected at a high enough frame rate (24 frames per second or more), the persistence of vision allows the eyes and brain of the viewer to merge the separate frames into a continuous moving picture.

An overhead projector (often abbreviated to OHP), like a film or slide projector, uses light to project an enlarged image on a screen, allowing the view of a small document or picture to be shared with a large audience.

In the overhead projector, the source of the image is a page-sized sheet of transparent plastic film (also known as "viewfoils", "foils", "acetate" or "transparencies") with the image to be projected either printed or hand-written/drawn. These transparent sheets are placed on the glass platen of the projector, which has a light source below it and a projecting mirror and lens assembly above it (hence, "overhead"). They were widely used in education and business before the advent of video projectors.

Qt Extended (named Qtopia before September 30, 2008) is an application platform for embedded Linux-based mobile computing devices such as personal digital assistants, video projectors and mobile phones. It was initially developed by The Qt Company, at the time known as Qt Software and a subsidiary of Nokia. When they cancelled the project the free software portion of it was forked by the community and given the name Qt Extended Improved. The QtMoko Debian-based distribution is the natural successor to these projects as continued by the efforts of the Openmoko community.

A home cinema, also called home theater, is an audio-visual system that seeks to reproduce a movie theater experience and mood in private homes using consumer grade electronic video and audio equipment for watching home video or streaming.

In the 1980s, home cinemas typically consisted of a movie pre-recorded on a LaserDisc or VHS tape; a LaserDisc Player or VCR; and a large-screen cathode-ray tube TV set, although sometimes CRT projectors were used instead. In the 2000s, technological innovations in sound systems, video player equipment, TV screens and video projectors changed the equipment used in home cinema set-ups and enabled home users to experience a higher-resolution screen image, improved sound quality and components that offer users more options (e.g., many Blu-ray players can also stream movies and TV shows over the Internet using subscription services such as Netflix). The development of Internet-based subscription services means that 2020s-era home theatre users do not have to commute to a video rental store as was common in the 1980s and 1990s.

A thin-film-transistor liquid-crystal display (TFT LCD) is a type of liquid-crystal display that uses thin-film transistor technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

TFT LCDs are used in television sets, computer monitors, mobile phones, video game systems, personal digital assistants, navigation systems, projectors, and dashboards in some automobiles and in medium to high end motorcycles.

Seiko Epson Corporation, commonly known as Epson, is a Japanese multinational electronics company and one of the world's largest manufacturers of printers and information- and imaging-related equipment. Headquartered in Suwa, Nagano, Japan, the company has numerous subsidiaries worldwide and manufactures inkjet, dot matrix, thermal and laser printers for consumer, business and industrial use, scanners, laptop and desktop computers, video projectors, watches, point of sale systems, robots and industrial automation equipment, semiconductor devices, crystal oscillators, sensing systems and other associated electronic components.

The company has developed as one of manufacturing and research and development (formerly known as Seikosha) of the former Seiko Group, a name traditionally known for manufacturing Seiko timepieces. Seiko Epson was one of the major companies in the Seiko Group, but is neither a subsidiary nor an affiliate of Seiko Group Corporation.

A video wall is a special multi-monitor setup that consists of multiple computer monitors, video projectors, or television sets tiled together contiguously or overlapped in order to form one large screen. Typical display technologies include LCD panels, Direct View LED arrays, blended projection screens, Laser Phosphor Displays, and rear projection cubes. Jumbotron technology was also previously used. Diamond Vision was historically similar to Jumbotron in that they both used cathode-ray tube (CRT) technology, but with slight differences between the two. Early Diamond vision displays used separate flood gun CRTs, one per subpixel. Later Diamond vision displays and all Jumbotrons used field-replaceable modules containing several flood gun CRTs each, one per subpixel, that had common connections shared across all CRTs in a module; the module was connected through a single weather-sealed connector. Eventually these cathode-ray tube-based technologies were replaced by LED arrays.

Screens specifically designed for use in video walls usually have narrow bezels in order to minimize the gap between active display areas, and are built with long-term serviceability in mind. Such screens often contain the hardware necessary to stack similar screens together, along with connections to daisy chain power, video, and command signals between screens. A command signal may, for example, power all screens in the video wall on or off, or calibrate the brightness of a single screen after bulb replacement (in Projection-based screens).

An ultra-high-performance lamp, often known by the Philips trademark UHP, is a high-pressure mercury arc lamp. These were originally known as ultra-high-pressure lamps, because the internal pressure can rise to as much as 200 atmospheres when the lamp reaches its operating temperature. It was developed by Philips in 1995 for use in commercial projection systems, home theatre projectors, MD-PTVs and video walls. Unlike other common mercury vapor lamps used in projection systems, it is not a metal halide lamp, as it uses only mercury. Philips claims a lifetime of over 10,000 hours for the lamps. These lamps are highly efficient compared to other projection lamps – a single 132 watt UHP lamp is used by DLP manufacturers such as Samsung and RCA to power their DLP rear-projection TV lines. It is used in many LCD and DLP video projectors.

A transparency, also known variously as a viewfoil or foil (from the French word "feuille" or sheet), or viewgraph, is a thin sheet of transparent flexible material, typically polyester (historically cellulose acetate), onto which figures can be drawn. These are then placed on an overhead projector for display to an audience. Many companies and small organizations use a system of projectors and transparencies in meetings and other groupings of people, though this system has been largely replaced by video projectors and interactive whiteboards.

The Nikon Coolpix S1000pj is a compact digital camera manufactured by Nikon released in September 2009 as part of the Nikon Coolpix series. The S1000pj is the world's first compact camera to feature a built-in projector.

Micromirror devices are devices based on microscopically small mirrors. The mirrors are microelectromechanical systems (MEMS), which means that their states are controlled by applying a voltage between the two electrodes around the mirror arrays. Digital micromirror devices are used in video projectors and optics and micromirror devices for light deflection and control.

An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector. To display images, LCD (liquid-crystal display) projectors typically send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red, green and blue components of the video signal. As polarized light passes through the panels (combination of polarizer, polysilicon LCD panel and analyzer), individual pixels can be opened (made transparent controlled by electricity) to allow light to pass or closed (made opaque controlled by electricity) to block the light. The combination of open and closed pixels can produce a wide range of colors and shades in the projected image.

Metal-halide lamps are used because they output an ideal color temperature and a broad spectrum of color. These lamps also have the ability to produce an extremely large amount of light within a small area; current projectors average about 2,000 to 15,000 American National Standards Institute (ANSI) lumens.