[argyllcms] Re: Characterizing a scanner using Argyll
- From: "Asman, Andrew J" <Andrew.Asman@xxxxxxx>
- To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx>
- Date: Mon, 2 Feb 2009 11:00:55 -0500
>
>I'm surprised to hear of delta E's as large as 100, unless you are
>significantly out
>of gamut. The best way of addressing this issue is simply to expand the gamut
>of your test chart to include these colors. The other approach is to try and
>choose a model that better represents the underlying characteristic of
>the device, rather than being as general as clut. You could try shaper/matrix,
>or gamma/matrix for instance, but you will probably be trading off a worse
>in gamut fit for a better out of gamut fit. This is assuming that the scanner
>has an underlying behaviour that is close to a per channel compression curve...
>
>Graeme Gill.
Expanding the gamut of the test chart is difficult because the gamut of the
test chart is directly
tied to the gamut of the printer that was used to create the profile. In
general I have found that
the accuracy of a profile is a give and take between the gamut of the printer
and the
uniformity of the patches on the target. In the past I have attempted to
actually print on top of
a previously printed target in order to increase the gamut. However,
misalignment issues
caused the uniformity of the patches to decrease which offset the gamut gain.
Do you have
any suggestions for "artificially" increasing the gamut of the test chart in
such a way
that wouldn't drastically degrade the uniformity?
Andrew
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