Re: OCIO Configuration Reference Values


Troy Sobotka <troy.s...@...>
 

On Mon, Oct 24, 2016, 6:55 AM Thomas Mansencal <thomas.m...@...> wrote:

Quick question: assuming you had primaries / whitepoint stored on a per colourspace basis, wouldn't that be competing with the OCIO MatrixTransform if not metadata? I can see a danger of disconnection between the primaries / whitepoint fields and the MatrixTransform if both are present at same time, precision issues induced by the rounding would be enough to break that relationship for example.

I tend to agree on the per-colourspace concept, given that OCIO cannot deduce between a well-defined colourspace and an EOTF etc.

What *is* required is a method to query metadata about the reference, in an absolute colour encoding model / space such as XYZ, given that OCIO is blind to the hard data on a space.

So what *might* be a solution is to provide a "one way" set of data as per specification or particular reference setup. Of course this could lead to minor discrepancies between say, white point via specification and white point via mathematical matrix calculation, but I suspect in this case the specification would be ideal?

Consider the currently, *all* OCIO UI is broken in terms of pickers and like details given that no existing method to formally query the reference metadata exists. Also consider that all CGI with regards to shaders / algorithms that require Kelvin, wavelength, etc. cannot work correctly without bending OCIO.

It should be noted that while a huge chunk of applications fail miserably that are within an ICC system, the methods exist for developers to "do the right thing" and glean information from the ICCs.

This is also required in OCIO, and should be a much more pressing subject given that *every single new Apple product* is using alternate primaries in their displays. Sure, we can hack around this by providing a reference role that takes things to XYZ etc., but a more official method would be preferred.

You would also likely need to support a field for the chromatic adaptation transform being used to convert from the given colourspace to the reference colourspace.

Probably going to be handy to have at least WVK, VK, and B, indeed. Is there any data out there on CAT02 and such regarding suitability for CGI / VFx work?

Can we see some motion on this?

With respect,
TJS

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