Rgby?

[aerials]

I know for years RGB has been the primary color for television. And it always looked quite good for a long time. Now Sharp has introduced a new system of RGB and now Y which is yellow. I remember our Wescott ctc-5 and the green hues it had back in the day. And I have seen it in person on the set I gave Wayne. Will this be a new trend in flat screen LCD and my preference plasma to add yellow? The 4 quad pixel set is called the Quattron. it seems to be in a LCD and LED version.

[jr_tech]

The approximate range of colors that the human eye can perceive is shown in the 1931 chromaticity chart (Kelly Chart) shown below:



The range of colors that can be generated, by a decent blue, an orange- red, and a yellow-green (not unlike the phosphors in color TVs) is contained within a fairly small triangle. If a decent yellow can be added at the right edge, then perhaps a green with less yellow can placed near the top left of the chart, greatly increasing the range of displayed colors contained within an odd shaped 4 sided figure. Getting past the limitations of the 3-gun CRT color (did anybody produce a 4-gun CRT?) may be a real plus for flat screen display.


jr

[old_tv_nut]

This is somewhat of a gimmick. Sharp demonstrates it with pictures of brass instruments, which are a more highly saturated yellow.

A display with standared sRGB primaries produces a good range of color, somewhat weak on the cyans and also (but less so) on the yellow saturation. This can be fixed by using only three higher saturation wider gamut primaries. The problem with expanding the gamut by any of these methods is that it is phony to just turn up the saturation on everything unless the source is coded with a higher gamut of color. There are proposed standards for wide gamut color in DVDs and Blu-Ray discs, but I don't think any wide-gamut discs have been released.

People who have bought wide-gamut displays for their computers have run into various problems when software doesn't recognize the color management aspects of this and the color saturation gets artificially increased. Also, since the color on LCDs varies with viewing angle, these variations are stronger when the primaries are more saturated. Using four or more primaries reduces the viewing angle variation, so that is one good aspect of using that method.

You should also realize that the 1931 diagram posted above emphasizes the size of the green/cyan area. Plotted on a uniform chromaticity chart, the missed area in the magenta and purple part is about as big as that in green.

[kx250rider]

My wife heard about this system, and I'd like to go see it in operation. As we know, the fundamentals of color TV since the CBS-RCA war in the 50s ended with Tyrant (oops; I mean General) Sarnoff's tri-color kinescope winning, we've been on the RGB standard worldwide. Maybe someone with engineering background could offer more, but I'm thinking there's no way to demodulate a 4th color, not to mention that every studio camera and every media player would be incompatible with a 4-color system.

Heck, if it can work, how 'bout I put a 3rd demodulator tube in my Zenith roundie, and call it the y minus y demodulator. But wait, since y=luminance in the RGB system, what the heck would we call the yellow subcarrier????

Yes, I'm poking fun.

Charles

[jeyurkon]

The Mitsubishi DLP's also add yellow, cyan, and magenta. But they are derived from the normal RGB information so it's not clear why they would help. Maybe it's just easier to calibrate. I think it must be more than advertising hype because most people wouldn't base their considerations at this level.

John

[TubeType]

Originally Posted by old_tv_nut

This is somewhat of a gimmick. Sharp demonstrates it with pictures of brass instruments, which are a more highly saturated yellow.

A display with standared sRGB primaries produces a good range of color, somewhat weak on the cyans and also (but less so) on the yellow saturation. This can be fixed by using only three higher saturation wider gamut primaries. The problem with expanding the gamut by any of these methods is that it is phony to just turn up the saturation on everything unless the source is coded with a higher gamut of color. There are proposed standards for wide gamut color in DVDs and Blu-Ray discs, but I don't think any wide-gamut discs have been released.

People who have bought wide-gamut displays for their computers have run into various problems when software doesn't recognize the color management aspects of this and the color saturation gets artificially increased. Also, since the color on LCDs varies with viewing angle, these variations are stronger when the primaries are more saturated. Using four or more primaries reduces the viewing angle variation, so that is one good aspect of using that method.

You should also realize that the 1931 diagram posted above emphasizes the size of the green/cyan area. Plotted on a uniform chromaticity chart, the missed area in the magenta and purple part is about as big as that in green.

You've hit the nail on the head. It's a gimmick. If the source isn't transmitting discrete yellow information, the Quattron receiver must be creating it from the transmitted RGB information. Also, if you add a fourth, yellow, pixel to the RGB scheme, you must reduce the number of RGB pixels to make room for yellow.

[Indian Head]

From the original 19th century demonstration by Maxwell, RGB has been the basis for every additive-color reproduction system, and it has worked very well.

I agree this is more gimmick than anything else, but the commercial is a hoot!

http://www.youtube.com/watch?v=4hSnAxvRdmY

OH MY!

[jr_tech]

"Also, if you add a fourth, yellow, pixel to the RGB scheme, you must reduce the number of RGB pixels to make room for yellow."

Or did they increase the number of pixels on the display to add the yellow?

"OH MY!"
Indeed... fun commercial!

jr

[wa2ise]

The main reason RGB works so well without yellow, is that the human eye has red, green and blue cone cells, and the brain sees yellow when some specific ratio of response from the green cones and red cones happens. A color CRT produces red and green light in the same ratio, tricking our brain to think that there is yellow light present. But a spectrascope looking at the CRT would only show a spike at green light frequency and another spike at red light frequency, and nothing at the yellow light frequency.

[jeyurkon]

Originally Posted by wa2ise

The main reason RGB works so well without yellow, is that the human eye has red, green and blue cone cells, and the brain sees yellow when some specific ratio of response from the green cones and red cones happens. A color CRT produces red and green light in the same ratio, tricking our brain to think that there is yellow light present. But a spectrascope looking at the CRT would only show a spike at green light frequency and another spike at red light frequency, and nothing at the yellow light frequency.

That is how we see, but the phosphors have a broader emission spectrum and are not monochromatic. A laser LCD or DLP would behave as you describe though.

John

[jeyurkon]

Here is a white paper on improving the color gamut by using multiple colors.

http://www.videsignline.com/showArti...leId=184425677

John

[jeyurkon]

Originally Posted by jeyurkon

Here is a white paper on improving the color gamut by using multiple colors.

http://www.videsignline.com/showArti...leId=184425677

John

With my DLP set it seems like what they are doing is artificially stretching the Rec. 709 gamut to match their expanded gamut.

Although I am for the most part pleased with the color of the set, this would explain a few odd things I notice. Whenever a scene contains a color near the one of the points they use to define the gamut, the color becomes a little too intense to be realistic. This doesn't show up on most scenes. Where I notice the most is with blue. Some shades of blue jump out at you. Normal sky blue is o.k.

I'm also red/green color blind so others might see effects I'm missing.

John