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Glossary Multimedia / Term

Graphics Grade Projector

Cathode ray tube video projector with a maximum horizontal scan rate of 63,000 Hz making it capable of displaying line quadrupled video and S-VGA graphics at resolutions of 1,024 by 1,280. Graphics projectors are the most versatile types of video display available (along with light valve systems). They can display any video format and nearly any computer graphics format (with the exception of 1,200 by 1,600 resolution images). raphics grade projectors top data projectors and video projectors for versatility based on the horizontal scan rate. Data grade projectors can display line-doubled video and VGA graphics (640 by 480 resolution) with a horizontal scan rate of 31,500 Hz. Video projectors are able to display traditional NTSC video formats (but not digital television and HDTV) with a horizontal scan rate of 15,750 Hz. he maximum vertical resolution of a projector (the number of horizontal lines drawn) can be determined by dividing the horizontal scan rate by the refresh rate (the vertical scan rate). The refresh rate used for video is 60 Hz (60 cycles per second resulting in 60 screens per second). By this formula, a graphics projector can produce up to 1,050 horizontal lines or a vertical resolution of 1,050. A data grade projector can furnish 525 horizontal lines and a video projector can furnish 262.5 horizontal lines. he interlaced video format used by the analog NTSC television standard specifies that two fields create a full frame so that there are 30 frames per second. Each field thus contains 262.5 lines (each line spaced apart by one blank line; all the odd lines are drawn and then all the even lines are drawn in the next field to create a complete frame). When the two fields are combined, the NTSC standard allows for 525 horizontal lines of resolution (although only DVD approaches using those 525 lines with laserdisc using only 425, cable television around 300 and VHS tape just over 200). he highest format of digital HDTV features interlaced 1,080 horizontal lines. Thus every one sixtieth of a second, a field of 540 lines is created with two fields combining for a total of 1,080 lines in a frame. Graphics grade projectors can easily produce HDTV video as they can output 1,050 horizontal lines of resolution (when only 540 lines are created at a time). Data grade projectors will generally be able to show HDTV signals as well. Of course, both graphics and data grade projectors will need new digital television tuners capable of receiving and decoding HDTV signals to present them. Graphics grade projectors are the most versatile form of video display, but they are also the most costly at roughly double to triple the cost of a standard CRT video projector (light valve projectors are more costly still and more versatile but are not common in consumer video).

Permanent link Graphics Grade Projector - Creation date 2021-01-07


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