RGB to become RGBCMY

elgatozorbas writes "The basic color elements of television have not changed much since 1954; a half-century after RCA introduced the first color set, the RGB (red, green and blue) system used then still prevails. But Israeli company Genoa Color Technologies has broken the RGB barrier by adding one to three primary colors such as yellow, cyan and magenta, thus expanding - from 55 to 95 percent - the coverage of the visible color gamut. The promised result of this multi-primary color (MPC) technology is a television picture that, with its truer, more vibrant color and brighter image, looks more like cinema than video. Also covered in IEEE Spectrum."

Comments

MPC: possibly the next standard?

[r_glen]

Does this mean I should hold off on buying an HDTV?

This will be great for Tetrachromats

[Anonymous Coward]

It's almost enough to make me wish I was a mutant mother of a color blind son.

Re:This will be great for Tetrachromats

[QuantumRiff]

That article explained alot. My GF asked me to hand her a her red shirt. I did.
She said, Thats ruby, i meant the red one.
So i handed her one of the other red ones.
No, thats rose,
On and on this goes, and then i finally tell her to pick the damn red shirt herself, she goes into the closet, takes a look at the 12 "red" shirts she has, and says, "see the red one, stupid". From what my buddies tell me, this is a very common issue, and perhaps these women have been overlooked for so long is that most of the doctors are men, and they just think the women are crazy. (My GF informs me that its really the other way around, we simple men are just blind!)

Biologically speaking, how...

[Walt Dismal]

Certainly makes one wonder what happened to three-color retinas...

Re:Biologically speaking, how...

[Cecil]

Yes, our eyes only have three types of cones, but unlike the color projected by a TV, they are not designed to respond to just one frequency of red, one of green, and one of blue. they have broad, overlapping response curves, each cone giving a different level of signal depending on the frequency of the light. The brain figures out the color based on the response of all three types of cones, not just the one that is active.

The stuff above is fact, the rest of this post is my pointless, unscientific, meandering hypothesis:

Obviously we use this concept with RGB signals to create colors like yellow, by tickling both the red and green cones at once with neighboring phosphors, but since the two colors are coming from very very slightly different places, the brain is not necessarily satisfied that it really is the color yellow. Basically, the more spectrum we can cover natively, the less chance there will be of someone's brain mumbling "that color doesn't seem... right"

Re:Biologically speaking, how...

[osu-neko]

Nothing. This just provides a better way to stimulate them. If one had the technology to vary the intensity of red, green, and blue over an infinite set of real values, then RGB would be able to perfectly replicate any color. In reality, the RGB color model used in displays today varies these values over a finite set of integers. One gets the best ability to reproduce colors that are red, green, or blue. Colors between these on the spectrum can be simulated by mixing these, thanks to the three types of cones we used to process color on the retina, but if in order to reproduce a particular color, we need 255 parts red to 41 parts green, we simply cannot increase the intensity of this color without distorting it (shifting towards green, because we've already maxed red). Thus, any RGB color model is going to more accurately and vibrantly display reds, greens, and blues, and simpler blends of these (where all values are equal, e.g. cyan), anything else is going to be limited in the range, grosser in steps between intensity, and less vibrant at the max. Adding pixels that display actual yellow (light of precisely that wavelength, rather than a blend of red and green wavelenght light exploiting the trick to stimulate our red and green cones to the same levels that actual yellow-wavelength light would), adding these pixels would increase the ability to accurately display these between colors, despite the fact that, in theory, only RGB is necessary. It's easier to add more between color pixels than to up the intensity range and lower the steps between intensities.

Re:Biologically speaking, how...

[iabervon]

The human brain rarely says something isn't the right color. There's a huge amount of slop in the brain needed to produce the perception of stable colors of objects under different lighting conditions (if you light a room with light blue light, your eyes will adjust and report the usual colors of objects, even though the light reaching your eyes from them is obviously different).

The real issue is that, since the curves overlap, the green phosphor triggers the red cone to a certain extent, so green plus blue is cyan plus a bit of red, or a bit less cyan plus a bit of white. So the most pure cyan you can trigger in the eye with an RGB screen is less pure than the most pure cyan you get find in the real world. Purple is more of a mess (since the brain is actually making up colors for combinations that aren't generated by any pure wavelengths, and faking the idea that red is next to violet). But it all comes down to limits on the saturation of different colors due to not being able to keep from stimulating some cone or other.

Nice, but still shortsighted

[krog]

A truly revolutionary idea would be to include and project IR and UV in addition to RGB/CMY. Even though our eyes can't exactly 'see' IR and UV, they still form an important part of our realistic image perception. It's not unlike sounds above 20-25kHz in pitch; we don't 'hear' them, but our brain perceives them nonetheless and they are used for stereo imaging of a space.

Re:Nice, but still shortsighted

[baryon351]

Those sounds are also felt by other parts of our bodies than ears. I once rescued a small bat, and while it was recuperating, from time to time it would open its mouth and squeal its echolocating squeal. While I couldn't hear it, my partner and I could feel the noise in our chest & neck. I also spent some time videotaping the bat as it flew around the room ready to be released. Whenever it did its noise thing, the levels on the VCR shot way up high and all the other audio dropped out. Powerful stuff, and while it's still sound it was perceived in far different ways than just ears.

Re:Nice, but still shortsighted

[pslam]

It's not unlike sounds above 20-25kHz in pitch; we don't 'hear' them, but our brain perceives them nonetheless and they are used for stereo imaging of a space.

No, our brain does not perceive sounds much below 20Hz or above 25kHz, and our ears are physically incapable of receiving them in the first place, unless it's loud enough of course (in which case you feel it instead). I have never read any convincing evidence to the contrary in any paper that isn't written by either a vested interest, or by someone who clearly isn't in expert on the subject (usually those go hand in hand).

On the other hand, our eyes do perceive more than RGB. The rods have a slightly different spectrum response than cones, so you need a 4th primary probably centered around its maximum response to get closer to fooling human vision. You can see this effect for example on the leaves of trees at sunrise and sunset. A TV really is just a visual trick - it's emitting just enough of the spectrum to look like the real thing. If it makes your rods and cones respond in the same fashion as the real image would, it doesn't need to do any more. I'm unconvinced that adding 3 more primaries is really necessary.

Coming soon, a computer for TV!

[ackthpt]

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.

... The promised result of this multi-primary color (MPC) technology is a television picture that, with its truer, more vibrant color and brighter image, looks more like cinema than video.

Right. Right when we've got all these plants around the world cranking out inexpensive TV's using LEDS and LCD, some whizzo comes along and says, "Hey, look, a great idea and all you have to do is retool everything, develop some newer technology and keep selling it all at the same pricing you're currently at!"

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, ...

Yay, now we really will need a computer in every TV! More components - more to go wrong, more power consumption, etc.

"How the algorithm does that, precisely, is a secret well kept by Genoa. "It's part of their intellectual property," Stone says.

Yay, more intellectual property. This should drive prices down.

<curmudgeon>
Why, back in my day we didn't have remote controls and we had a folded playing card stuck beside the tuner knob to keep the picture from doing funny things, and we liked it!
</curmudgeon>

I'm sure it will look lovely, while watching older stuff from the bad old pre RGBCMY days.

"Gilligan!"

I'm like, totally there, dude!

I know you're being sarcastic but . . .

[bodrell]

Far violet (~400nm) and far red (~700) are both visible. They might make the viewing experience much richer, and light at those wavelengths won't damage skin / eyes or cook your dinner.

Re:Color Space

[DreadPiratePizz]

This is true, but more colour depth is often needed in compositing work. It's not uncommon for a visual effects shot to be handled at 16 bits per channel, or twice the colour resolution of a 24 bit image. The reason is that it has a greater dynamic range. If you add two bright pixels together, the result will be white. But with more bits per channel, the pixels will be brighter than white, and still maintain values relative to other pixels, so that if you darken them later, no information is lost. Visually, 24 and 48 bit colour are indistinguishable.

Larger gamut.. *yawn*

[Animaether]

I'll wait for HDR display and feeds, thanks.

Judging from the gamut chart for this RGBCMY, the boost in color range is primarily in yellows and cyans. Gold, as they note, would be a good application. Cyan.. well, that's mostly skies - and those already appear just fine on TV. A fairly decent increase in magentas/purples as well (when taking the assymetric lobe into account), but again.. not seeing its application much.
Unless following the British royal family (lots of golds and purples) a lot, it doesn't appear to offer all that much. Especially considering movie people butcher things anyway (DVD gives a more stable picture, sure.. at the compromise of mpeg artifacting and even encoding issues.. twitches ever 25 frames are annoying - luckily only a few suffer from this).

On the other hand, a higher dynamic range would be immediately noticeable anywhere.
A sequence with the sun glaring into the camera ?
A car's headlights shining at the camera ?
Highlights on objects ?
Blown-out surfaces from bright lighting ?

All that could then more accurately be represented. And thanks to most things still being shot on film, or already on 10bit CCDs with, formally, underexposure but a gain for the operator, a good bit of extra range is already available in previous and current productions.
Whilst RGBCMY would only really be of use for film (as in, actual film) productions, as digital cameras are in much the same RGB limbo that current displays are.

Wide gamut displays

[baxissimo]

Wow, this is really cool.

There's a whole bunch of these wide gamut and high dynamic range displays suddenly.

At SIGGRAPH this year, there was a 6-primary (RGBCMY) projection system called IRODORI on display in emerging technologies:
http://www.siggraph.org/s2004/conference/etech/iro dori.php?=conference

There was also a high dynamic range display (capable of a greater range of brightness) from Sunnybrook Technologies at E-Tech:
http://www.siggraph.org/s2004/conference/etech/hig h.php?pageID=conference

And then I saw a few displays on the exhibition floor from NEC with a "WG" specifier for "Wide Gamut". NEC's WG monitor is still RGB but with purer R, G, and B phosphors to obtain a gammut wider than Adobe RGB.

And now there's this one. Way cool.

I can't wait till this becomes more widespread. The question becomes, what will the next color standard be for use in applications and APIs? It doesn't make sense to actually encode color as 6 values for display, since (most) humans only have three kinds of cones. It would make more sense to use something like CIEXYX for color interchange in that case. Especially if we're going to have this wierd mix of HDR and various wide gamut displays around for a while, each which has slightly different needs for color output. Best to just go with a neutral, well-defined intermediate colorspace.

IRODORI six-colorn display at SIGGRAPH

[peter303]

Last week in the emerging technology section of SIGGRAPH a company or process called IRODORI was demoing a six-color projection system. (I could not find a reference on Google or www.siggraph.org.) When side-by-side with a conventional three-color you saw dramatic differences. Conventional is like looking at the world with wax-paper taped over your eyes. They claimed that conventional systems only covers about 55% of the CIE color chart, while they get over 90% color space. They bootstrap off of two conventional three-color projection systems. They put in different color filters and add special color separation software.

New standard still necessary

[MunchMunch]

From the article: "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.

And here's what you said: "This isn't a new standard, it's just an after effect applied to existing signals."

While you're right that it can be used in transitional technology, you're wrong that it's "just" an after effect. Nobody would say that Technicolorized B&W reproductions are the same as actual full-color originals. And here, you're going to need a format that preserves color information in the new 5 color system if you're going to exploit the real improvements in this color technology: closer reproductions of actual color.

Re:New standard still necessary

[cmowire]

It's probably simpler than you think.

CMY are really "combinations" of R G and B.

So, what's happening is that they are tossing in "intermediate" colors in roughly the same way as a 6 or 7 color printer. The exact equations are probably proprietary, but the process is pretty standard.

This comes in to play at two places. First, HDTV has a pretty ambitious color gamut, so videos designed around the HDTV gamut will look better, assuming of course that the source footage is equally high quality.

Second, there are colors that your eye can perceive that are not representable by the RGB system.

Overall, the research is already done. There's actually quite a few different ways to represent this data. PhotoCDs already use it. You want to use L*a*b or XYZ or one of the other CIE color systems.

I think it's interesting, but when I read the headline, my first thought was "Gee. What took them so long?"

Re:New standard still necessary

[Cuthalion]

CMY are really "combinations" of R G and B.

This is false. C, Y, and M are different wavelengths of light from R, G, and B. Because the human eye only has receptors for R, G, and B, we can't distinguish between equal quantities of R and G and a single wavelength in between the two, namely Y. In other words, we are able to trick the eye into perceiving a full color spectrum using only three different wavelengths of light.

Re:New standard still necessary

[The Snowman]

I had never tried to think outside the RGB world because it 'technically' displays all colors, though it struck me that the colors in-between RGB will come out dimmer than they should.

No, RGB technically displays more discrete colors than our eye can see. That does not mean it "displays all colors." There are some colors RGB displays that we cannot distinguish between, and there are some colors we can distinguish that RGB cannot display.

Go caving sometime

[freeweed]

There's a huge amount of slop in the brain needed to produce the perception of stable colors of objects under different lighting conditions

Boy, you can say that again. For anyone who *really* wants to experience this, I suggest you go caving some time. In a deep enough cave that no outside light penetrates. Last weekend myself and a group were out, and we all had different models of headlamps. Now, the cave we were in has 3 interesting things going for it here: very banded & multicoloured rock, lots of ice (again somewhat multicoloured due to how it forms over the centuries), and human artifacts (a fair bit of paint on the walls, general human refuse, etc).

Here's the trick: you're in an area where your eyes have never seen the surroundings in natural light. Effectively, you have no reference point to know what colour things are. Now, I personally have one of the newer LED/incandescent combo headlamps (an amazing combination by the way, and for those with any doubt, 3 white LEDs will provide more than enough light for at least 20' around you - no more trying to focus right in front of your feet :). Alternating between the LEDs (white light) and the bulb (yellow light) was... interesting. My eyes couldn't decide what colour things were. Relatively speaking, sure. But I'd go for a while with just the LEDs, my eyes got used to that, then switch to the bulb. Suddenly, switch to the bulb, and everything gets weird. Even subtle things like depth cues get messed up, because your brain is frantically trying to re-colour what you're looking at.

This really didn't happen with things like our clothing or other gear, because my brain "knew" what colour that stuff was, having seen it outside, and it adjusted easily. But the rocks, ice, and *especially* the tagging on the walls - very creepy effect. Things that looked green in one light could be red in another. The ice was fun, because it's actually somewhat brown/yellowish in some layers (dirt, I suspect). But the brain wants to colour it blue-white.

We also had a good game of "guess my eye colour" - many of these people didn't know each other very well. I think we scored less than 50% overall :)