An HD projector is a device for displaying a video signal in a resolution higher than a standard television. The HD stands for high-definition, which can have a variety of designations and types. Projectors can be used in a variety of ways. While previous projector technology was more appropriate for slideshows and presentations, the technology has evolved a great deal. Today projectors are used for videogames, movies and television.
High-Definition Resolution
High-definition resolution is defined simply by being of a higher quality than standard-definition. Standard-definition televisions display images at a resolution of 640x480 pixels. High-definition comes in a few standard forms. The first is known as 720p (1280x720 pixels). The highest grade of high-definition projection commonly available is 1080p, which is 1920x1080 pixels.
P versus I
HD projection comes in two basic varieties: progressive and interlaced. Interlaced scanning is when the image on the screen is refreshed one half at a time. The lines of pixels alternate changing with each cycle. While the overall effect is very smooth, because the screen refreshes at a rate faster than the human eye can see, there is a notable drop in clarity. Progressive scanning simply refreshes every pixel at once, with every power cycle. The "P" at the end of 720p or 1080p indicates that the image is progressively scanned and, therefore, more clear.
Light Output
An important component of high-definition is projection is the light source and power. The light is what pushes the image through the lens and produces the bright screen that makes projection so desirable. The amount a projector produces is described in lumens. The more lumens, the brighter the final image.
Projection Surface
What separates an HD projector from a standard television is that the projector and the screen are separate, but equally necessary, components. A projector is only a projector when the image is being displayed on a surface. This surface can be a specialized screen or a white wall.
Formats
HD projectors cannot simply produce high-definition images. Instead, they are dependent upon a device and a medium that can provide a high-definition signal. The HD projector is the tool used to present a high-definition signal. High-definition video can come from HD cable broadcasts, video game systems or high definition video formats, such as Blu-Ray and HD-DVD.
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