[Tig] Backward compatibility for new video standards.

Richard Kirk richard at filmlight.ltd.uk
Fri Sep 6 16:29:34 BST 2013


On 09/06/2013 03:51 PM, Joe Owens wrote:
> You obviously don't work for Apple.

No, but I am not above/below inventing video standards. When we 
discovered that the ITU tone curve was defined for cameras, we went and 
measured a number of Sony BVM CRT monitors of the day, and made the 
Truelight SonyHD calibration. This had a 4000:1 tone curve fitted using 
an arbitrary but quick to calculate formula. This was not video as we 
know it, Jim, but it served as our best guess for what a client might 
see on a well set-up BVM. This was close to the ITU rec-1886 tone curve, 
but it did not go to zero light and zero gradient at zero.

> Being involved with the struggle between distribution formats, my main 
> gripe is that there are simply too many, and none of them are well 
> understood, and the decision-makers and distributors for the most part 
> don't know there are actually any differences at all.  (Its "just 
> video", right?)

People making high gamut displays do not want to develop new video 
apparatus before they can show a working product, so they grab as much 
of the existing video hardware as they can use, and stick in slightly 
different RGB values. Then, you have 4K video, so the data won't ever 
cross over into 2K or HD or whatever without going through some 
converter, and that is when you stick in the colour transform.

I have the nagging suspicion that a word in the right ear at NHK or 
somewhere could get the 4K standard changed before they have made too 
much kit.

> Help me out here...  there were a couple (and they were a married 
> couple) of color researchers from the mid-80s who were trying to 
> convince the recommendation-makers that an entirely log/log approach 
> to color difference and gamma would do away with most of this 
> space-transform/display complicatedness.  The Glenns?  Seems to me a 
> golden opportunity was missed.

Today, they might be suggesting floating point XYZ video, or something 
equally scary.

Cheers.
Richard Kirk

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