A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings. Video projectors are widely used for many applications such as, conference room presentations, classroom training, home theatre and concerts. Projectors are widely used in many schools and other educational settings,[1] sometimes connected to an interactive whiteboard to interactively teach pupils.
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A video projector, also known as a digital projector, may project onto a traditional reflective projection screen, or it may be built into a cabinet with a translucent rear-projection screen to form a single unified display device.
Common display resolutions for a portable projector include SVGA (800×600 pixels), XGA (1024×768 pixels), 720p (1280×720 pixels), and 1080p (1920×1080 pixels).
The cost of a device is determined not only by its resolution but also by its light output. A projector with a higher light output (measured in lumens, “lm”) is required for a larger screen or for a room with a larger amount of ambient light.[2] For example, a light output of approximately 1500 to 2500 ANSI lumens is suitable for small screens viewed in rooms with low ambient light; approximately 2500 to 4000 lm is suitable for medium-sized screens with some ambient light; over 4000 lm is needed for very large screens or for use in rooms with no lighting control such as conference rooms.
A few camcorders have a built-in projector suitable to make a small projection; a few more powerful "pico projectors" are pocket-sized, and many projectors are portable.
With a growing do-it-yourself (DIY) community and an increasing interest in low cost devices, some hobbyists have endeavored to build their own projectors from kits, sourced components, or from scratch. Through the internet, the community is now able to obtain plans to construct DIY-video projectors.[3] There is a growing trend toward building them for domestic requirements and classroom use. The DIY-projectors are now being used both in developed countries and in developing countries in the interest of providing education as well as for entertainment purposes.