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Coming Soon: Trillion-Color TV

Technology promises to bring the color of cinema to home TV sets

3 min read

You sink into the couch and start to play a DVD on your big-screen TV set, ready for some cinema-quality entertainment in the comfort of your home. But something is missing, even if you might not notice it, and it's not the gigantic popcorn bucket. It's real color, says Genoa Color Technologies Ltd., an Israeli company in Herzlia Pituach.

While film used in cinema contains pigments that can create an infinitely large number of color variations, TV sets combine discrete amounts of red, green, and blue light to create a much more limited color range. To produce more colors, TV sets would have to combine purer, or more saturated, red, green, and blue by using narrowband light filters that select colors more precisely but diminish brightness at the same time.

Genoa says it has developed the software and hardware necessary to close this gap and make TV images more cinemalike without the unwanted dimming side effect. The trick is to add extra primaries, the basic colors that, combined, form all others. By adding yellow and cyan (a light blue) to the standard red, green, and blue, a display that could normally generate about 16.7 million colors would now be able to show more than one trillion [see diagram, " Color Craze"].

"This is quite a revolutionary idea," says Abhay Sharma, an associate professor in color imaging at Western Michigan University, in Kalamazoo. He says that in printing it's common to have inkjet devices that use six, seven, or even eight primaries. "But this is the first time I have heard of trying that in display systems."

Genoa developed a color conversion algorithm that runs in a special microchip to be added to a television's imaging circuit. The algorithm gets a color value--from a DVD, for example, that the television would originally exhibit as a combination of three primaries--and finds how to best represent it as a combination of five primaries.

Genoa partnered with Royal Philips Electronics NV, in Amsterdam, Netherlands, to implement the new color technology by modifying a family of rear-projection TV sets, which rely on liquid-crystal-on-silicon (LCOS) technology. In their current configuration, these sets produce images by shining red, green, and blue light from filtered white light onto a small microchip embedded with millions of tiny pixels made of liquid crystal that modulate and reflect the light to a lens system. This set of lenses amplifies the image and projects it on the screen, where red, green, and blue light overlap to form secondary colors.

Adding two extra colors to this kind of projection television has little impact on the price tag, says Simon Lewis, vice president of marketing at Genoa. He says the new Philips color-enhanced set, to be available next year, needs only a few additional filters and optical components to create the yellow and cyan light, with no changes to the more costly microprojection chip.

Perhaps the main challenge in converting a video stream from a three- to a five-primary color system is doing it in real time, says Maureen C. Stone, an independent consultant in the Seattle area and an expert in digital color. It's not easy, she says, essentially because there are simply too many colors--every fraction of a second, millions of colors change on the screen.

What's more, such color conversion is not always straightforward. If the color data is from a person's skin, for example, the algorithm has to determine, among a multitude of possibilities, the exact combinations that produce natural skin tones, with smooth hue gradations as opposed to abrupt color changes.

How the algorithm does that, precisely, is a secret well kept by Genoa. "It's part of their intellectual property," Stone says. What's certain, according to her, is that even though Genoa's technology increases the range of colors, it's not recovering the full original color information of a movie on film, lost in the conversion to other formats, like DVD. "It's kind of arbitrarily making images look better," she says, though people will in fact prefer the resulting colors, which will typically be more saturated and brighter.

In a demonstration showing the overall color improvement, Genoa's multiprimary system exhibited colors that current television sets cannot display [see photos, " Color Craze"]. Sometimes, however, saturation seemed excessive, with colors glowing too intensely onscreen, and that may require some adjustments.

Other than that--and the lack of a popcorn bucket--the system's color abundance proved a truly cinematic experience. Whether or not the colors were truer to life, they were more satisfying.

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