[Carl B]

Sony announced yesterday the creation of 'x.v.Color,' a branding methodology with associated logo whose purpose is to provide consumers with a simplified means of identifying xvYCC-compliant displays in anticipation of retail availability later this year.

Featured by Sony in a technology demonstration at last year's Consumer Electronics Show, xvYCC is a colorspace standard that allows for the display of roughly 1.8 times the color range allowed by present industry standards (ie RGB). In conjunction with the expanded bit-depths permitted through 'Deep Color,' compliant devices outputting via HDMI 1.3 to compatible 'x.v.Color' displays will be capable of putting on screen nearly every color found in nature that is visible to the human eye.

Originally proposed by Mitsubishi and Sony through the Japan Electronics and Information Technology Industries Association as a new standard for the consumer electronics industry, xvYCC was approved as an official international standard by the International Electrotechnical Commission early last year. Mitsubishi and Sony are presently also the manufacturers considered most likely to release xvYCC-compliant displays in 2007; Mitsubishi through retail sets utilizing their laser-DLP technology, and Sony through LCD.

Presently, Sony's Playstation 3 is the only consumer device on the market supporting HDMI 1.3 and capable of outputting a 'Deep Color' image. Presumably, the Playstation 3 could also gain xvYCC colorspace output via a future firmware update, similar to the recent YCrBr output enabled on the console by SCEI.

[Carl B]

It should be noted that there are presently xvYCC-compliant Bravias for sale in Japan at this time, but hey that's Japan...

[Rufus]

Does anyone have a good pointer explaining xvYCC? A bit of quick googling just says it's "Extended-gamut YCC". They're obviously throwing more bits in for a larger color space, but where are they throwing the bits?

[Basic]

You could think of it as making the RGB values signed. It's easy to get the impression that there would only be black there, but there's actually deeper colors on that side. So if you have some positive red, you could add some negative green and blue to make it even deeper red.

But the exact format? Can't help you. (Most likely not signed RGB though. )

[wishiknew]

Thanks XBD for the japanese Bravia info. Contrast ratio went up a bit. Can't tell if it has hdmi 1.3 but I assume so due to xvYCC. Can't Hope to see the model appear in NA soon.

[Carl B]

Yeah that Japanese Bravia does have HDMI 1.3... the x2500 series is what you're looking for.

@Rufus210: The deep color and the xvYCC are actually two different capabilities that can complement each other. For example, Deep Dolor still has utility within RGB and YCrBr; it greatly expands the number of 'shades' that can be displayed from within those colorspaces. Should help reduce banding in the real world, etc...

xvYCC on the other hand, expands the the range of displayable colors on the CIE 1931 chromacity diagram to encompass over 90% of human-perceptible color. NTSC/RGB/YCrBr on the other hand encompass only about 50% of 'color.'

'Deep Color' would be used in conjunction with xvYCC - similarly tp how it is used with RGB etc... - to greatly expand the number of 'shades' available within that now also greatly expanded colorspace.

Basically, given an 8-bit per component output source:

* xvYCC would grant you a greatly expanded range of colors, but the shade range would be spread even more thinly than it is within the present RGB (ie ~17 million 'colors' within a greatly expanded color range)

Given a 12-bit per component 'Deep Color' source:

* You now have 68.7 billion colors/shades to work with within whatever colorspace. Within RGB, you basically have seemless color, and even within xvYCC - where Deep Color works great in conjunction - you approach nearly the entire range of visible color in what is still a seemless fashion of shading.

[rendezvous]

Originally Posted by Basic

You could think of it as making the RGB values signed. It's easy to get the impression that there would only be black there, but there's actually deeper colors on that side. So if you have some positive red, you could add some negative green and blue to make it even deeper red.

I'm having difficulties trying to imagine an output device outputing negative colours.

[Basic]

It's not really negative colors. It's just that the common RGB coding is such that you need negative values to reach them. We have three kinds of cones in our eyes, they react (mostly) to red, green, and blue. It's easy to get the impression that the Red, Green, and Blue values in the framebuffer is mapped straight to stimuli of the respective cone. But they aren't!

First, the RGB values are defined to match the colors you get from three phosphors in a CRT. That's not pure monochromatic colors.When you say "all red" to the monitor, you'll get a small amount of other colors too. That's not (only) because of electrons leaking to the nearby green and blue dots, it's because the red phosphor doesn't give a pure red color. Same things goes for the other two components.

Second, the cones in your eyes detect overlapping color spectra. Even with a monochromatic green light, you'd still detect it to some extent with the red and blue cones too.

Those two effects add up, so if the framebuffer has RGB = (1.0, 0.0, 0.0), your eyes will get some stimulation for other colors than red. The "negative G and B" is just to compensate for the wanted red that "leaks" into the green and blue channel of you eyes.

Practcally, you could of course not have a negative light. It's just a way to say where the "new" colors are relative a RGB color cube. Instead, you'd need more pure colors (closer to monochromatic). Ie, fixing the first factor described above. And that's what the new monitors do.


As a side note, the second factor above is still there. And that can't be corrected by just making the red, green, and blue light more pure. The only way to compensate for that is to use more than three base colors in the monitor. It can still be encoded as three values, but the physical pixels on the monitor would need more than three color components.



For an illustration, look here. Scroll down to the "Current RGB color space" image in the middle of the page. The corners of the triangle represent the colors of the three phophors. The inside of the triangle is the colors that can be represented with this standard RGB space. The curved edge represent pure monochromatic light (the wavelength is ploted in the image). If you want to get outside of the triangle, you'd need one or two of the RGB components to be negative. As I said above, that's fine in theory but not physically, so you need a larger triangle instead. Mitsubishi uses lasers for their new DLP, so they will get the corners right out at the curved edge.

But even with three ideal corners, there'll still be some colors outside the triangle. The only way to reach more of those is to approximate the space with a polygon with more vertices. And more vertices here means more base colors than red, green, and blue.


Sorry if I'm rambling...

[Simon F]

Originally Posted by xbd

Sony announced yesterday the creation of 'x.v.Color,' a branding methodology with associated logo whose purpose is to provide consumers with a simplified means of identifying xvYCC-compliant displays in anticipation of retail availability later this year.

Does anyone know if there are any public docs describing xvYcc? I could only locate an abstract.

[Carl B]

Not sure... but searching for technical standard IEC 61966-2-4 would probably be the best way to locate a full description, if indeed one is publically available.

[Simon F]

Originally Posted by xbd

Not sure... but searching for technical standard IEC 61966-2-4 would probably be the best way to locate a full description, if indeed one is publically available.

Tried that but with no luck as present