[argyllcms] Re: FWA Compensation
- From: <robert@xxxxxxxxxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Mon, 8 Dec 2014 11:53:12 -0000
Hello Jan-Peter,
Yes, the image has 3 strips (marked "D65 fluo OBC", "D65 fluo" and "D50" one
above the other). Each of the strips is from the same image (so same
RGB/Lab data). When I created the image I made sure that all the colors are
in gamut for the target profile.
The illuminant is a D65 fluorescent and the paper is a Permajet Oyster.
Looking at the SPD of the paper it does seem that it has a lot of FWA as
there is quite a big hump around 400nm. I don't know how much UV is in the
lamp. Could you tell me how I can estimate this doing an M1/M2 measurement?
(using spotread, I assume?).
I produced 3 profiles, the first being the default D50 profile, the second
one with illuminant compensation for the fluorescent lamp, and the third one
with FWA compensation for the fluorescent lamp. I then printed the strips
using Relative Colorimetric from Beta RGB (which was used as the source
profile in colprof as you can see).
I then stuck the strips on board, one on top of the other, and photographed
them under the fluorescent lamp.
Robert
_____
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Jan-Peter Homann
Sent: 08 December 2014 10:12
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: FWA Compensation
Hello Robert, hello List
Is it correct, that you the photo represents prints, which are based on the
same RGB-data, converted to each printer profile, printed all out and than
compared under D65 light ?
Which rendering intent you have used ?
Please consider, that the profiling software tries to compensate the
lightning / OBA influence in this case.
You should also consider, that there different strategies for paper makers
to create papers with a cold bright paperwhite.
One is the usage of OBA and another the usage of bluish whitening agents.
Such things are best detected, if you compare M1 and M2 measurements of the
paperwhite.
Furthermore, it can be the case, that your D65 lightning has only low UV
content in the lightning spectra.
Regards
Jan-Peter
Am 08.12.14 09:58, schrieb robert@xxxxxxxxxxxxxxxxxx:
Graham,
I've done a test which I have posted on Luminous Landscape, here:
http://www.luminous-landscape.com/forum/index.php?topic=95251.msg782782#msg7
82782
I would appreciate you having a look at this post as the results are not
what I would have expected (actually, they are the opposite of what I
expected). Could be that I'm confused.
Here are the commands I used for standard D50 illuminant, D65-Fluorescent
illuminant, D65-Fluorescent illuminant with FWA compensation:
colprof -v -ACanon -MiPF6400 -Dprofile -qh -SBetaRGB.icc -cmd -dpe
-Oprofile.icc profile
colprof -v -ACanon -MiPF6400 -iprofile-D65-Fluorescent.sp
-fprofile-D65-Fluorescent.sp -Dprofile-D65-Fluorescent-FWA -qh -SBetaRGB.icc
-cmd -dpe -Oprofile-D65-Fluorescent-FWA.icc profile
colprof -v -ACanon -MiPF6400 -iprofile-D65-Fluorescent.sp
-Dprofile-D65-Fluorescent -qh -SBetaRGB.icc -cmd -dpe
-Oprofile-D65-Fluorescent.icc profile
Thanks
Robert
--
homann colormanagement ----------- fon +49 30 611 075 18
Jan-Peter Homann -------------- mobile +49 171 54 70 358
Herzbergstr. 55 FG 3.01 -- http://www.colormanagement.de
10365 Berlin ---------- mailto:homann@xxxxxxxxxxxxxxxxxx
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