Du bist on the right track.
I have not seen your results BUT regardless of how you adjust the raw scan,
over-expose, under-expose, the profile is supposed to give you the same
results. (??!!)
If you want to edit the profile, you are supposed to edit the converted IT8
-- not the target scan.
As long as it arbeit for you...
MfG / Roger
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Hermann-Josef Röser
Sent: Monday, March 13, 2017 4:47 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] AW: Re: AW: Re: ICC-profile shift histograms
Good morning Roger,
thank you for your detailed instructions. Unfortunately I only have
PhotoShop Elements. So I cannot follow your recipe perfectly. However, I can
use other tools like RawTherapee or imageJ. I had analysed the delta E (I
have written an EXCEL macro to set up a batch for Argyll, which makes life
much easier for me than using the command line. And it always includes
profcheck to analyse the histogram of deltaEs and also does a second
iteration with the high deltas clipped.). That all looks normal.
The problem is the calculation of Lab-values from the target scan once the
profile is applied. Different tools (SilverFast, RawTherapee, imageJ, Bruce
Lindbloom's calc page) give different results.
What I have done is following the advice by Fraser et al. (2005), who
recommend editing the profile, if one is not happy with the results. One
always has to edit in the opposite direction as one would like the profile
to react. So in my case, if the profile produces results which are too dark
(bright) one has to make the target scan darker (brighter). To achieve that,
I use scans with different settings of the analog gain (which effectively is
the exposure time). Standard is 150, so if the profile produces shifts to
the left, I use an analog gain of e.g. 120, which reduces the shift. I hope,
this is the correct procedure.
I would have thought that there is one of the many switches in Argyll, with
which one could adjust the profile.
Best wishes
Hermann-Josef
