Re: Perceptual Javex
Re: Perceptual Javex
- Subject: Re: Perceptual Javex
- From: Graeme Gill <email@hidden>
- Date: Fri, 22 Sep 2006 01:53:52 +1000
eugene appert wrote:
I have a limited understanding of the inner workings of icc profiles. I
am noticing an anomaly with the perceptual rendering of a specific
scanner transparency profile written by Monaco Proof. Using perceptual
It's hard to comment without the actual profiles, or at least some
more details. Is it a matrix profile, an XYZ PCS Lut profile,
or a L*a*b* PCS Lut profile ?
Note that the standard way profiling input devices operate,
is that the white point of relative colorimetric rendering
will be taken from the white patch of the profiling target.
Since the ICC way is to store all profile data as relative
colorimetric, and the L*a*b* encoding can't encode L* values
above 100, the result is that L*a*b* PCS Lut input profiles will
saturate for any device value input above that of the test charts
white patch. Also note that for a Lut (ie. table based) profile,
some profiling programs have poor behaviour outside the gamut
exercised by the test chart - ie. they don't extrapolate well.
Graeme Gill.
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