[argyllcms] Re: Camera matrix profile, adding ti3 perfect white data set

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 01 Feb 2010 14:21:08 +1100

Elle Stone wrote:

I'd be happy to send you the .ti3. What e-mail address should I use?


Just send it to graeme@xxxxxxxxxxxxxx


Actually the same gamma correction is needed with both matrix and cLut
profiles (though I don't actually use any type matrix with my camera
except single gamma matrix). This 1.04-1.05 necessary gamma correction
is constant across several target shots under different lighting
(direct sun and indoor hi-cri florescent).


Hmm. I understand what you mean, but I'm really not sure how
one would go about creating such a thing, since a cLUT inherently
tries to fit in each local region. Either some sort of
luminance re-scaling is needed, or converting all the samples
to constant luminance and then fitting a 2D cLUT to the result
would be needed, and then expanding it back to 3D.
Or is there some other approach possible by manipulating the
original samples ?

Assuming the apparent gamma is caused by flare, then
effectively it is necessary to remove the flare from the original
readings so that the profile doesn't attempt to compensate for it,
but what flare model should be used, and how is it determined ?

Graeme Gill.

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