My advice,
Try processing the raw image outside Silverfast to PROVE to yourself that
the ICC profile is doing its magic.
Meine frage ist that, how does the farben of der image appear to you in
Photoshop, regardless of the pixel conversion to follow?
Is it gut? Dark? Saturated?
It might be a fact of your scanner's response that certain farbe need
shifting the Red values down considerably to match the expected Lab values.
It's entirely possible.
Compare the performance of the scanner on the IT8 image itself, FIRST. What
is the DeltaE like?
If the pixels are converted by the profile, there has to be a gut reason.
This is easy to do. Just open up the raw IT8 scan (from which you create the
scanner profile) in Photoshop, assign the profile to the image, and compare,
one little patch at a time, the Lab of the IT8 image and the Lab of the
resulting image, after assigning the scanner profile.
(Make sure you select Absolute Colorimetric under Color Conversion Options
in Photoshop's ColorSettings).
It is not necessary to look at every patch of the IT8, just analyze those
patches that you find suspicious.
You have to find a way to build confidence in the arbeit of der profile.
Delta E color difference is very good for that analysis.
/ Roger
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Hermann-Josef Röser
Sent: Sunday, March 12, 2017 4:12 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] AW: Re: ICC-profile shift histograms
Good evening Roger,
Thank you for your answer.
I am using SilverFast HDR. I have the raw (linear) scanned image loaded,
which is gamma-corrected by HDR. Then the ICC-profile is applied and the
output image is converted to Adobe RGB (1998) colour space. In HDR I see
two histograms, the input histogram and the output histogram. If I turn off
colour management I see as input the gamma-corrected data without
ICC-profile. If I then switch on colour management with the ICC-profile of
my choice the colours in the displayed image change and the input histogram
changes in the way I described: it shifts left or right, in some cases it
stays put. Unfortunately one cannot show images here.
If I split the histogram into the three channels I can see e.g. that it is
the red channel, that saturates at dark values. The colours look okay.
I use imageJ to look at the pixel values. The output image in Adobe RGB
indeed has the red channel saturated at low values. So it is the pixel
values themselves that are changed by HDR.
Hermann-Josef
