I am sure that. at least in the US, people have started seeing the new ad campaign for Sharp’s new television - claiming a new color combination of RGB and Yellow.
Supposedly, the addition of yellow will make it possible to add colors (such as brass, gold and other similar metal/colors) that make things look better.
I am a bit dubious - but have yet to see what it looks like. Then again, the “coming soon” part of the ad seems to imply I cannot run to my local electronics store and see what it looks like to prove or disprove their claims.
This is the only link I could find from Sharp, but doesn’t go into much detail.
Has anyone actually seen this television, and does the addition of Yellow really add to the quality of color on the screen?
Sounds like marketing bullshit. The human retina has only green, red, and blue receptors (cone cells) and current technology is sufficient to reproduce all 32,000,000 shades of color which the human eye can detect.
Maybe adding a yellow pixel makes the golds more golden, or the brasses more brassier, but on the surface it sounds like pure snake oil.
The colors you can see on a color TV are found in a polygon on the CIE diagram bounded by the sources. For a standard RGB screen, that means you see everything inside a triangle bounded by the chroimaticity coordinates of the three phosphors. These don’t give all the colors you can see with natural white light sources, but it gives you most of the visible range.
In principle, you can extend this range by adding more sources. If they add a yellow source, that triangle can turn into a quadrilateral, and you’ll be able to see a sliver more of real colors.
This diagram shows the real color space, and the embedded triangle shows the space achievable with three phosphors:
Yoellow would be off to the side around 570, and it doesn’t look as if it would add much, based on the diagram. You’d think they add a new phosphor around, say, 520, and get that big chunk in the upper left. I should point out, however, that the diagram doesn’t give you equal portions of energy or of visibility. Your eye is more sensitive in the green, and yellow is pretty close to that. Yellow might be the optimum choice in expanding obviously visible color values.
The biggest problem I see is that your TV signal only broadcasts for the RGB signal (and, I believe, black and white) – it doesn’t have the information needed to accurately add the portions for a fourth color. The only think I can see is that they’re somehow interpolating the information, generating it from the broadcast tristimulus color. That means not merely adding some yellow to the mix, but also in changing the relative proportions of Red, Green, and Blue as well. I can see this going awry occasionally, and giving some goofy color mixes.
by the way, the fourth signal isn’t “overkill” because we only have three receptors – nature broadcasts in essentially infinite sources. The three phosphors don’t coincide with the sensitivity of our three receptors, so it’s not as if there’s a one-to-one correspondence. Anything that gets us closer to reality is arguably a better picture. But, until everyone is broadcasting signals corresponding to the output of the TV, the system is going to be something of a kludge.
I get a picture in my head of the filming of this commercial with the director and Takai having an argument: “George, we need you to gay it up a bit for the Star Trek fans.” G: “If it gets any gayer, you’d have to add a pink receptor!”
That CIE diagram is an ideal RGB color space though. On most TVs the gamut will probably be smaller and be a different shape depending on brand.
I don’t know how Sharp works their technology, but I’d almost guess that the new yellow phosphor is close to where the current green location is, and the “new” green is somewhere in the green/cyan range in the upper left. This would expand the gamut to a quadrangle.
I wonder how that fits into the old DLP TVs that used color wheels. My 6 year old Samsung DLP TV uses a color wheel with the following colors: Red, Blue, Green, Magenta, Yellow, Cyan and White (clear). So does that mean DLP TVs had superior color reproduction?
The human eye does indeed have three types of color receptors, but they do not absorb only certain colors, like RGB, and mix them like a television does to display an image. the three types of cones are each sensitive to a wide range of wavelengths. This image from Wikipedia shows the response from each cone at different wavelengths.
Because the human eye can not resolve the resolution of individual pixels from a television set, the addition of a yellow pixel will not change how our eyes interpret the colors, but will only increase the range of colors, as Cal has so excellently described.
It’s because the yellow ranger was a male in the original Japanese production, the costumed footage of which was reused for the American version. They wanted to add another female (besides pink) to the lineup for the American version, so they picked the smallest (and lightest-colored) of the remaining rangers and made “him” a girl.
Agreed, the “sweet spots” for enlarging the color space are not the pure Red/Green/Blue/yellow points. The goal is to maximize the area of the enclosed space, and if one could develop a pure aqua or teal LED or phosphor, then that would have far greater effect than adding a yellow corner would. I’ll also drop this additional link for the Macadam ellipses, which overlays ranges where a shift in color becomes human-perceptible.
The current color triangle works pretty well, though. The only colors left are the 1950’s melamine and designer naugahyde furniture palette, which are probably best left unseen to the naked eye
