A wide gamut color system would reproduce colors beyond the existing Rec. 709 gamut.

So suppose you displayed a 100% red 0% green 0% blue on your existing monitor (e.g. the computer monitor you have right now). There is a red that is even more pure than the red you're seeing. Things like laser pointers and lights reflecting off a CD/DVD can reproduce reds that vivid/pure. Some LED-backlit LCDs can also produce reds purer/more saturated than normal reds.

2- In a wide gamut system, you need to specify a wider range of colors. If you use the same number of bits, then those bits are spread thinner. Too "thin" and you will see banding artifacts. So you need to jump to 10-bit.

3- Personally I don't think wide gamut color (at the consumer level) is that good an idea. Granted... this is not having really seen a wide gamut system in practice.

One of the inherent problems is that not all displays can display wide gamut colors / colors that fall outside normal Rec. 709 gamut. So colors will look different on those displays compared to wide gamut displays. You'll definitely still be stuck with NTSC- not the same color.

The 10bit HDMI interface and the x.v.colour thing may not be unrelated as only devices with HDMI 1.3 support it. There's some scant information on it here.
To further confound us, x.v.Colour had the moniker xvYCC but that got changed as it was too much for the punters to say.
There's more info on xvYCC here. If I read that correctly then it only becomes possible to display the larger gamut on LCDs using LED backlighting.

About the only place that might have any real technical information are the Society for Information Display but unless you're a member you have to pay to get a copy of the document.

Bob.

You beat me too it!

What you're saying pretty much is what I was thinking but some of the words from Sony *seem* to imply that existing LCDs cannot display the full gamut of Rec 709. To further compound the issue there's also "Deep Colour" thrown into the mix.

The summary of the SID article that I'll not pay to read implies that this system provides a wider gamut than film is capable of.

Your last comment about "NTSC" is right on, the cameras that do shoot x.v.Colour do say not to engage this unless you have a suitable display device. OK, fair enough. But these are only cheap palmcorders and they're sure as heck not recording 10bit!

Even more confusingly one article implies that all this is about is using computer RGB to get the wider gamut instead of sRGB.

As for your comment at 3). Amen! Probably not as tragic as those DVD camcorders in the hands of the consummers but still, I can see some wonky images coming to a giant screen in a loungeroom.

Bob.

LCDs cannot display the full gamut of Rec 709.
They can. With current systems, they can't display beyond that.

2- With current Rec. 709 systems, black level is put at 16 (Y') and white level at 235 (Y'). That range stores values within the normal Rec. 709 gamut. By using negative + out-of-range numbers (that result in values below black and above white), you can define colors that lie outside Rec. 709 gamut.

*(engineering detail) The Rec. ?1361? transfer function gives a definition to how the negative numbers map.

Ok anyways, the current scaling of video puts legal values in the 16-235(Y') range (and 16-240 for chroma values). There is some leeway to define wide gamut colors.

2b- To define all possible visible colors, you need to change the scaling/range from 16-235 to something else. (Which I can't remember off the top of my head.) This lets you define all possible visible colors, which the 16-235 range doesn't let you do.

3-
"Deep color" = 10-bit or higher bit depth
You need this for wide gamut.

xvColor is presumably:
HDMI 1.3: The receiver can figure out that it's receiving wide gamut colors and do appropriate image processing.
Changing the range of Y'CbCr values to something other than 16-235. And using the Rec. ?1361? transfer function. This lets you specify any visible color (the display may not be able to display it- this is up to the display).

Maybe the spec you're thinking of is CIE 1391?

Think I've got it sort of in my head now!

So x.v.Colour (xvYCC) is using 1 to 254 to get a larger gamut.

All this sounds like the display manufacturers came up with these new displays that could display a wider gamut than 709 but they wouldn't sell too many if they had no content to feed them. That'd explain why we're seeing this in consummer palmcorders first.

Must try shooting something with one of these cameras in x.v.Colour and see how it looks in Vegas.

Bob.

CIE 1931 is not a spec... it is the set of color science data/experiments that a lot of current standards are based on.

2- All this sounds like the display manufacturers came up with these new displays that could display a wider gamut than 709 but they wouldn't sell too many if they had no content to feed them.
DCI is another reason why the home video/theatre manufacturers are interested in wide gamut. They want theatre quality in the home.
DCI supports wide gamut... so they want to support wide gamut too.

2b- The original NTSC system was essentially a wide gamut system. The original NTSC primaries (the exact shade/chromaticity of red, green, blue) is much greater than what we have now. Incidentally, Adobe adopted that as their working space (Adobe RGB and the original NTSC primaries are the same).

The original NTSC primaries were abandoned in an effort to make displays brighter. (Which was a big problem with CRTs at that time.)

Right now, we have pretty bright displays in LCDs.

Bob, in Vegas 8, you can see a subtle difference in color with footage shot with xv. The only cams we have with xv are the small HDV cams and AVCHD cams, but looking at the same footage in 8 vs 7, it's much more rich.