[argyllcms] Re: Profile generation with perceptual intent with compensation for paper white
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 22 Sep 2017 13:37:37 +0200
Am 22.09.2017 um 10:10 schrieb Henrik Olsen:
I notice ArgyllCMS documentation says "The pa intent, Perceptual Appearance...
The intent -ipa is likely close to your desire, it is obviously supposed to
preserve the CIECAM02 appearance, and additionally does gamut compression.
As with all CIECAM02-based intents, you need to specify the source and
destination viewing conditions with the options -c... and -d..., and you
can also override the source and destination adapted white points with
the command line optiosn -cw:... and -dw:...
However, on the command line, you cannot override the "D" parameter of the
CIECAM02 model (-> degree of adaptation), it is always calculated automatically
from the other specified viewing condition parameters. Typically, the calculated
value lies in the 0.8...0.9 range. If you want to force it to 1.0, then it seems
you need to patch xicc/ciecam02.c.
With the patched code and overriding -cw:... and -dw:... I can obtain an almost
perfect perceptual D50 gray axis with collink.
[ However, different from the commercial "neutral" profiles, even paper white
itself gets neutralized by printing yellow ink, while the gray axis of the
commercial
profiles still cheats, beding from D50 towards blue-ish paper white in the upper
20% of the axis. ]
Regards,
Gerhard
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