x.v.colour ??

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Joined: Mar 14 2006

Anyone got any details on this I saw a commnet about it have 1.8 times the detail of RGB and being used my some (probably consumer) HD cameras, but no real info other than this below;

Q: What is meant by the term “Deep Color™” and why is it important?
Deep Colorâ„¢ lets HDTVs and other displays go from millions of colors to billions of colors allowing consumers to enjoy unprecedented vividness and accuracy of color on their displays. Deep Colorâ„¢ eliminates on-screen color banding, for smooth tonal transitions and subtle gradations between colors. It enables increased contrast ratio, and can represent many times more shades of gray between black and white.
Q: What is “xvYCC”?
HDMI 1.3 adopts use of the IEC 61966-2-4 color standard, commonly called xvYCC (shorthand for Extended YCC Colorimetry for Video Applications). This new standard can support 1.8 times as many colors as existing HDTV signals. xvYCC lets HDTVs display colors more accurately, enabling displays with more natural, vivid colors .
Q: What is the difference between “Deep Color™” and “xvYCC?”
Deep Colorâ„¢ increases the number of available colors within the boundaries defined by the RGB or YCbCr color space, while xvYCC expands the available range (limits) to allow the display of colors that meet and exceed what human eyes can recognize.

so the real question is can we use this stuff? is it the future?

Nick Hampson,
1x3Hz Brain cell, 10 fingers than never hit the right keys, 2x MkI eyeballs (used).
Disclaimer - the user is not responsible for any bad spelling and grammar in this post, it is entirley the fault of Microsoft, Apple, HP, Dell, Adobe, Avid, Autodesk or whoever you dont like this week.

Alan Roberts
Alan Roberts's picture
Joined: May 3 1999

xvYCC is intended to extend the colour gamut beyond that of the nominal aim primaries of the transmission system (ITU709 for all HD). It allows the R'G'B' (gamma-corrected RGB) vaues to go below zero and above unity, but you need a decoder and display that handles these signals properly to get any benefit from them. The principle is that the display primaries can be different from those of the system, and the decoder can perform a matrix transcode into the correct colour space for each display. However, the R'G'B' signals have to be returned to linear RGB by an inverse gamma correction to do this properly, and the matrixed RGB values then have to be gamma-corrected for the display. There's no way round this.

The information I have on xvYCC is somewhat sketchy, it implies that a gamma curve like that of ITU 1361 is used (bipolar) to allow negative values, but it doesn't explain how that gets handled in the transmission coding. The claim is that when the R'G'B' values are all within the normal range (0 to 1) the coding is the same as ITU709, but normal ITU709 coding doesn't allow for signals outside the normal range (16 to 235 in 8-bit), so it's a bit vague as far as I can see except that values 1-15 and 236 to 254 could be used (values 0 and 255 have special significance and shouldn't be used in transmission)..

I can't comment on "Deep Color".

Claims like "millions of " and billions of" colours are highly dubious at the best of time, the vast proportion of those colours are indistiguishable from other colours, because our perception of colour is very highly non-linear.

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Camera settings documents are held by Daniel Browning and at the EBU
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Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.