Is the 4th Yellow Pixel of Sharp Quattron Hype?

Nom du Keyboard writes "Sharp Aquos brand televisions are making a big deal about their Quattron technology of adding a 4th yellow pixel to their RGB sets. While you can read a glowing review of it here, the engineer in me is skeptical because of how all the source material for this set is produced in 3-color RGB. I also know how just making a picture brighter and saturating the colors a bit can make it more appealing to many viewers over a more accurate rendition – so much for side-by-side comparisons. And I laugh at how you are supposed to see the advantages of 4-color technology in ads on your 3-color sets at home as you watch their commercials. It sounds more like hype to extract a higher profit margin than the next great advance in home television. So is it real?"

Comments

Clearly missing a trick.

[queazocotal]

To get truly astonishing pictures, they should add a black pixel, to improve contrast.

Re:Clearly missing a trick.

[jjoelc]

joking aside... some of the newer TVs with LED backlighting actually do something like this... Lighting up the picture with thousands(ish?) of independent LEDs (as opposed to a couple of souped up flourescent tubes) means they can selectively dim or turn off entirely sections of the backlighting. So when large parts of the scene are dirk, large parts of the backlighting is dimmed as well, thus increasing the contrast. It also saves a bit of power, making it easier for them to meet energy star standards, etc...

RGB

[Kell Bengal]

It strikes me that a better use of a fourth colour pixel would be to represent all those greens the RGB colour space doesn't actually represent.

Re:RGB

[Anonymous Coward]

Only is the camera recording the picture recorded that same color.

As it has been stated, adding a new color on the TV is literally the last place that it needs to be. (First the camera that films, then the storage medium(DVD?), then broadcast(HDMI?) THEN the TV )

Re:RGB

[Anonymous Coward]

That 1931 color gamut is misleading because it overempasizes greens. In fact, the original NTSC green primary was much closer to the peak, but as a result, yellows were too muted, so they changed it. But you're right - a turquoise primary would increase the RGB gamut significantly.

The ideal would be that all color information in video would be in device-independent xy color space instead of RGB. See LogLUV encoding for example: http://www.anyhere.com/gward/papers/jgtpap1.pdf

Re:RGB

[forkazoo]

Only one problem. No Y encoded in the data stream, so it has to be interpolated.

In some cases, it could actually be useful. While most cameras shoot with RGB sensors, most video compression is in some variation of YUV (1) color space. If you shoot on something like a Red One (2) camera, you get a RAW format with more than 8 bits (3) of color information. If you have a sensible post pipeline, you can go to YUV for your distribution format and have plenty of color data to completely fill out the 8 bit YUV data. YUV and RGB don't have identical color reproduction and gamut, so you can wind up with the odd situation where you shot on an RGB sensor, and you decimated to 8 bit data for distribution, but a normal 8 bit RGB display can't quite show every color that you have.

I wouldn't expect brick-shittingly amazing results on such a system. I'd need to see it in person and see a measured gamut chart to have any particular opinion on this particular display, but I can't dismiss the concept out of hand.

(1) : Y in YUV isn't Yellow, it's Luma. Still, the imperfect conversion between YUV and RGB means that a fourth primary could make it possible to more accurately show YUV data on an RGBY display.

(2) : "Red" is a brand name. "Red" in the name of the camera doesn't specifically imply any relationship to RGB color space or anything like that. The camera does use a standard RGB Bayer pattern sensor, though.

(3) : 8 bit color in this context is always "per component" rather than "per pixel" and doesn't imply old school 256 total colors palleted mode. In a X11 config file for example, this would be referred to as 24 bit color. Video guys are more interested in per-component colors because they always do operations on components. When you are writing misc. GUI software, you are generally more concerned with bits per-pixel because you would never care about how much space it takes to upload a fraction of a pixel to a video card since you have to upload a full pixel to display it.

(4) : This footnote doesn't correspond to anything in the text. After all that, I'm now just in the habit of writing footnotes.

Re:RGB

[Twinbee]

Parent is correct. Any colours around green and cyan are usually terribly unsaturated on most monitors. In fact, even in 'real life', it isn't theoretically possible to experience true cyan/aqua because the nearest direct wavelength will stimulate the red eye cone to some extent creating colour pollution.

There is a trick around this, which can be found by over-saturating the red cone. This weakens it temporarily, and then when shortly afterwards you see anything resembling cyan, it will appear as close to the true qualia as you could ever expect. The "Eclipse of Mars" illusion that follows in the below link demonstrates this for those who are curious:

http://www.skytopia.com/project/illusion/2illusion.html

Re:RGB

[jipn4]

That's misleading. A lack of a fully saturated green on a monitor is a limitation with the phosphors or dyes it uses. But monochromatic light of around 515 nm is pure, fully saturated green. Fully saturated green stimulates both your M and L cones ("G" and "R" cones); that's the way your eye works.

You can achieve non-physical responses from your photoreceptors via oversaturation, drugs, or electrical stimulation. That's interesting, but it isn't "green" and it isn't a "true qualia". Thinking of that as "green" is simply because you think of the M cone as a "green" cone and the L cone as a "red" cone, but those are just arbitrary names.

Not necessarily fake

[russotto]

Adding an extra phosphor can extend your gamut, increase your dynamic range within your gamut, or give you finer quantization within the gamut, or some combination of all three. The fact that your source material is provided as three quantities (YCbCr, not RGB) doesn't mean four phoshors won't help.

Doesn't mean it will, either.

Re:Not necessarily fake

[kc8apf]

If you've ever had a display calibrated, you'd know that even the existing RGB color space can't be completely recreated with existing RGB-based displays. The problem is in the inability of LEDs or LCD or plasma panels to produce light uniformly in the three color channels. If you can add a 4th channel that lets the RGB color space be more accurately produced by the display, then you will see an improvement. It won't make the source any better, but the output generated by the display for that input will be better.

Re:Yellow... yawn

[uglyduckling]

Like Octarine?

What's wrong?

[rm999]

Representing yellow with a mix of green and red is already a hack. What's wrong with software determining that the color of a pixel is yellow and actually lighting up a yellow light?

Maybe a yellow light looks more convincing than a red and green light right next to each other. I'd want to see for myself before making blanket judgments.

Re:Yes

[LynnwoodRooster]

The red one, just like on Star Trek.

Pictures just about sums it up

[phantomcircuit]

http://regmedia.co.uk/2010/05/07/quattron_4.jpg That just about sums up the entire article.

Local dimming has a problem

[tepples]

A lot of TV sets that use local dimming have a big problem showing starfields. The average color in a starfield is pretty dark, so the LED goes dim and not bright enough to show the stars. It really takes the punch out of Star Wars Special^n Edition if you can't see the stars.