Re: [Lcms-user] LUTs in littlecms

[Kai-Uwe B. <ku...@gm...>]

Am 19.04.09, 01:58 +1000 schrieb Ignacio Ruiz-de-Conejo:
> Most of the time, the result is the expected one. But in all the different 
> profiles I have built, the tests show glitches, and I can find RGB values 
> that do not map to the desired output.
> It is weird, for instance, that clamping does not produce a clean, rounded 
> number. And the presence of mis-behaving values here and there, not only in 
> the border of the regions.
> Maybe the rounding and interpolation is a limitation I can't avoid,and with 
> deeper effects than I expected.
>
> You can find sources in http://docs.google.com/Doc?id=dfscpqm8_45t4q5ffst

Beside not being able to open your file, did you try the 
cmsFLAGS_NOTPRECALC flag for better precission? I would assume you are 
working already at 16-bit data.

lcms-2.0 will and SampleICC, an other open source CMM, can work on 
floating point data. I must confess that I have no idea about the real 
interpolation precission. I just know that film people really care for 
round tripping. If that requirement is sucessfully meet with the floating 
point 'mpet' tag kind of transforms is not known to me. But other have 
elaborated shurely and you may find perhaps even in the archives of this 
email list.

kind regards
Kai-Uwe Behrmann
-- 
developing for colour management 
www.behrmann.name + www.oyranos.org