I'm scratching my head over how to invert a LUT.
Mike,
That is indeed a very difficult topic. For properly inverting a LUT you have to know the gamut boundaries, and then proceed differently inside or outside gamut. I have done some experimentation with generalized Newton on n dimensions using Jacobians. Works well if the gamut hull is convex and the lut is "smooth" enough. You have to extrapolate ouside gamut. I have used a polinomial approach here, with little succes I should add :-(
lcms does not have such code, there is no need to do that strictly following ICC
spec. However, I would be interesting as a future addition, since this would solve
the issue about limited precission BToAxx tags exhibit...
Regards, Marti.
----- Original Message ----- From: "Mike Russell" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, February 26, 2005 12:27 PM
Subject: [Lcms-user] Inverting a LUT?
I'm scratching my head over how to invert a LUT.
I've looked over other, non lcms, examples, for example Argyll's makerev,
but since this must be a relatively common operation, I'm wondering if there
is an existing example using lcms.
Thanks, BTW, to Marti and others who helped with my previous question.
Mike Russell www.curvemeister.com www.geigy.2y.net
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