[argyllcms] Re: -S command in Colprof for printer profiles
- From: "Philip Reed" <philipreed@xxxxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Tue, 18 Oct 2011 20:36:38 -0400
Hi Gerhard,
I was also a bit confused about this relationship, but your excellent
explanation really made things clear.Thank You.
Phil
_____
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Gerhard Fuernkranz
Sent: Tuesday, October 18, 2011 4:27 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: -S command in Colprof for printer profiles
Am 18.10.2011 19:32, schrieb Alan Goldhammer:
It's likely that I'm a little dense on this but I've read Graeme's
documentation over multiple times regarding the use of this command and
gamut mapping. I want to make a profile for my printer and I've printed
patch targets and read them. How do I handle '-S' when I'm ready to run
Colprof? We don't know what the gamut behavior of the printer is at this
point only from research that it's broader than AdobeRGB1998 and smaller
than ProPhoto. ProPhoto is the default color space for Adobe Lightroom and
the recommended color space for Photoshop because of the larger gamut than
AdobeRGB1998. Does this mean that I should use '-SProPhoto.icc' in my
command line or use '-nS'. It's not clear to me and assistance would be
appreciated.
If you want the perceptual and saturation intents of the profile to do gamut
mapping from ProPhoto's gamut to the printer's gamut, then you should use
-SProPhoto.icc. This means that the perceptual intent of the profile will
compress the ProPhoto gamut hull until it can be completely completely
enclosed by the printer's gamut hull. This compression affects however _all_
colors inside the gamut. If the gamuts of many of your _actual images_
happen to be smaller than the ProPhoto gamut, then consequently the
perceptual intent of the printer profile may de-saturate many of your images
unnecessarily, just in order to be prepared to render any worst case images
(utilizing the _full_ ProPhoto gamut) w/o clipping. Choosing a reasonable
"one size fits all" source gamut is always a trade-off.
Regarding '-nS', I would expect that -nP and -nS don't have any effect if
the -S... profile is a matrix profile.
Btw, if the gamut of your printer is really as large as you assume, then I'd
possibly even try to print with relative colorimetric intent and don't care
about gamut mapping at all (I do have doubts though, that the printer's
gamut hull really encloses the Adobe RGB gamut hull completely, for instance
is the printer's black point really as dark as Adobe RGB black?).
Regards,
Gerhard
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