[argyllcms] Patching profiles with non-D50 illuminants for Absolute Colorimetric
- From: "Alastair M. Robinson" <blackfive@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 31 Aug 2005 01:03:46 +0100
Hi,
In a recent post in the Fluorescence thread, Gerhard said:
"Btw, keep in mind that Argyll records the mediaWhitePointTag in the
"traditional way", i.e. *not* adapted from the viewing illuminant to
D50. Thus, if you use a printer profile generated with "profile -iA ..."
for proofing with ICC-absolute intent, you may not get, what you expect,
if your expectation is an *illuminant relative* reproduction, as the
term ICC-absolute is interpreted by the ICC. In order to get the ICC
desired behaviour, you need to patch the mediaWhitePointTag and
mediaBlackPointTag accordingly in the Argyll generated profile."
How would one go about doing this? I've generated printer profiles
using measurements made with D50 illuminant and D65 illuminant. The D65
ones give noticeably more pleasing perceptual and rel. col. results, but
aren't much use for proofing as they stand. :)
How does one go about patching the white and black point tags? Are
there any appropriate tools or do they still need to be written? :)
Mathematically, how would the white and black points be calculated?
Would scaling a reference D50 whitepoint to match the Y component of the
measured point be sufficient or is it more complicated?
All the best,
--
Alastair M. Robinson
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