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July 2002|There's no question that the shift from raster-based imaging systems and bulky picture tubes to fixed-pixel, flat-matrix displays has opened up a new world of possibilities. From super-thin LCD screens and plasma panels to flexible, polymer-based displays for cars and portable electronics, you can pretty much watch video, data, and any mixture of the two wherever and whenever you want it. But there's a downside (isn't there always with new technology?), and that is the fixed-pixel arrays used in all of these new displays. Cathode-ray tubes (CRTs) may have been heavy and power-hungry, but they could scan any interlaced or progressive-scan image with no pre-determined limits other than the resolving power of the electron gun. All a CRT needs to scan and display a given signal is the horizontal scan rate, blanking interval, and vertical refresh. A 4:3 aspect ratio picture tube with a reasonably fine dot pitch is thus as equally adept with XGA (1024x768) graphics as it is with interlaced 525-line video. Not so fixed-pixel displays, which only look their best when the incoming signal is a 1:1 match for the available pixels. That's not too hard to accomplish when using a VGA display (640x480 pixels is pretty close to the scan line count of a video signal), but becomes progressively harder as resolution increases in non-standard multiples of video resolution. Things are further complicated by widescreen fixed-pixel displays with oddball resolutions. These unusual pixel counts (1280x768, 1365x768, 1365x1024, etc.) are often extensions of standard computer resolutions and bear little or no relationship to analog or digital TV standards like 704x480, 1280x720, or 1920x1080. The process becomes even more convoluted when converting interlaced video to progressive scan. Motion interpolation, luminance and chrominance filtering, and correction from 3:2 pull-up filmed material must all be dealt with. And once you've slogged through that obstacle course, the finished image then has to be re-sized up to fit the available pixels on the monitor or projector. It's no wonder that most video program sources—composite, S-video, even component—don't look very good on a majority of LCD and DLP projectors and LCD and plasma monitors. It's also no surprise that most manufacturers use HDTV content to show off these products at major trade shows—throwing away a little image resolution is not as difficult as adding a lot of it. While a few Asian display manufacturers are starting to get the message and adding expansion slots for aftermarket video processor boards (such as Faroudja/ Sage's FLI2200 de-interlacing chip set) and others are developing their own chipsets (like Fujitsu's AVM processor), the majority of displays still need help for high-quality viewing of video content. The Middleman
The answer is to use an outboard scalar, and there are several companies selling such products to interface with fixed-pixel displays. One notable company is Key Digital Systems of Riverdale, New York, a manufacturer of all types of video/ computer interfaces. Their entry into the digital scaling market is known as the model KD-HT1080p digital Leeza ($6199 including DVD player), and it's a rather unusual product. For starters, digital Leeza looks and behaves like a PC, except it's got a slew of BNC connectors on the back. You boot it up and load the operating system, and voilà—a full-blown video scalar with 15 different output resolutions (plus HDTV pass-through) awaits your next command. In a nutshell, Leeza takes your analog or digital video input sources and performs the decoding, de-interlacing, motion compensation, 3:2 correction, and upsizing functions described earlier. All you need do is to connect the output to your projector or monitor, and select the appropriate output resolution and vertical refresh rate to match your display. Typically, that output connection will be either analog RGBHV (tri-color with component sync signals, like a computer monitor), or YPbPr (a three-wire connection with luminance and sync on one wire and color difference signals on the other two wires). But Leeza doesn't stop there. You may also be able to make a direct digital connection from the scalar to your monitor or projector's DVI (Digital Video Interface) input connector, provided Leeza knows how to communicate with that particular display. In theory, this should provide you with the cleanest and most precise match and highest image quality. Following the theory that "garbage in equals garbage out," Leeza also has a Serial Digital Input (SDI) jack for direct connection of ITU-601 component 4:2:2 video from appropriate sources. One of those sources could be a progressive-scan DVD player equipped with an SDI output jack, such as those sold by Theta and Electrograph.
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