[argyllcms] Re: help with camera profile
- From: "alberto.ferrante@xxxxxxxxxx" <alberto.ferrante@xxxxxxxxxx>
- To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx>
- Date: Thu, 19 Jul 2012 09:14:07 +0100 (GMT+01:00)
Dear Iliah and Edmund,
thanks for your replies. Following my replies
to
your questions.
> when you mean "profile" do you mean Raw or Jpeg?
If
Raw, which converter?
Raw; the converter is ufraw, an open source
converter based on dcraw.
>First, how even was the light at shooting
the target, what was the light
>source, how much flare you are
getting, how linear is the greyscale step wedge
>on the shot, for
each
of 4 channels?
The light source was sunlight (in a day with
clear sky
with sun at the zenith). I used some black paper to shield
the target
from possible reflexes on the bottom and on the right and
left. The
illumination was even (I checked it on the images and,
before taking
the shot, with a Sekonic light meter). I do not see any
flare in the
image and I positioned the target to avoid glare as much
as possible (I
don't see any on the final image). I can post the
picture of the target
tonight when I get home, if it could be useful.
>Second, what colour target are
you using for creating the profile -
how does it
>warrant -qu for a
LUT-based profile?
I am using the
target made by Wolf Faust (coloraid.
de).
As I mentioned already, I
used it to profile other cameras in the
past.
> Third, how do you
obtain the source rgb image for profiling?
Is it through
> ufraw in
profiling mode?
Yes, through Ufraw, by setting the output to absolute
colorimetric, 16 bit, tiff, with no input
color profile and linear
base and output curves.
> Forth, why -al
instead of -ax; if not a -G
which is a much more stable solution?
I tried them both, but with no
good results.
In the past I tried all of the available profiling
options and at the end I preferred the -al, but
I am ready to change
my mind if any other option works better!
>
Fifth, does ufraw allow
for a linearization tone curves over all 4
channels? If
> not - ask
them to implement this option. If they are
unwilling, linearize
>
yourself. Linearity must be calibrated before
profiling.
Can you
please give me some references about this? What is
a linearization
tone curve?
Thanks again!
Regards,
Alberto
P.S. I apologize for
my previous post, but I hit the "send" button before the message was
ready...
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