Hi Graeme,
thank you very much for this clarification.
This brings up an issue I wanted to ask anyhow. I have read your
documentation on colour management but I do not really understand what I
have to do to make use of the different rendering intents.
The software I use (SilverFast HDR) to render the scans in Adobe 1998 RGB
allows me to select the rendering intent but it expects the corresponding
tags A2B0, A2B1 and A2B2. As far as I can see, Argyll always creates A2B0
and having read your webpage on colour management I do not understand how to
create the other tags. From what I read in the book by Fraser et al. (2005),
the above tags correspond to perceptual, colorimetric (absolute or
relative??) and saturation rendering.
I would appreciate your help here. Perhaps you can quote a source where I
can read and learn the relevant things :-).
With best wishes
Hermann-Josef
--- Begin Message ---Hermann-Josef Röser wrote:
- From: "Graeme Gill" <graeme@xxxxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Thu, 16 Nov 2017 13:37:40 +0100
Hi,
If I apply the profile created to the target scan, from which itoriginated,
the brightness of the whole image increases drastically. E.g. a patchwhich
in the (gamma-corrected) original raw image has a value of about 54500ends
up at close to saturation at 64000 with the profile applied.
that's quite normal with relative colorimetric intent since the white patch
of the
test chart will be mapped to perfect white, as per ICC. So A19 L*a*b* 78.37
-6.17 -3.15
becomes L*a*b* 100 0 0. If you want to preserve the absolute values, you
need to
use absolute colorimetric intent in your conversion.
Cheers,
Graeme Gill.
--- End Message ---
