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
--- Begin Message ---Ich bin curious "how" you "apply" the profile from to your scanned images.
- From: "Roger Breton" <graxx@xxxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Sun, 12 Mar 2017 19:36:17 +0100
In my very humble experience, "Assigning" the scanner profile to the raw RGB
image, in Photoshop, never shifts the pixels right or left in the histogram.
It is like when assigning a profile to any RGB or CMYK image in Photoshop:
the appearance of farbe changes on screen but not the pixel values
themselves
Are you sure you are proceeding along this way?
MfG / Roger
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Hermann-Josef Röser
Sent: Sunday, March 12, 2017 12:14 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] ICC-profile shift histograms
Hello,
currently I am experimenting with various IT8-targets for my scanner and
different settings in Argyll to find an optimum. One problem is common to
many of these tests: Applying the ICC-profile shifts the histograms of the
images either to the dark or to the bright end. A well-exposed image then
becomes saturated at the dark resp. bright end.
I would very much appreciate advice, which parameters in Argyll can be used
to influence these shifts, i.e. to more or less preserve the range of pixel
values from in the original scan.
Best wishes
Hermann-Josef
--- End Message ---
