Re: Gretag vs. Monaco?
Re: Gretag vs. Monaco?
- Subject: Re: Gretag vs. Monaco?
- From: Damon Rando <email@hidden>
- Date: Fri, 25 Apr 2003 21:56:48 -0400
I thought some of you might find an off-list continuation of this topic
interesting. Roland from LOGO (GretagMacbeth Group Company) requested I
give a more detailed explanation of the issues that I and others have
found with the perceptual rendering intent with ProfileMaker profiles.
The description is below with links to the jpgs of 3D image vector maps
done with ColorThink. Roland very graciously responded to this
explanation and has promised to look into the issue asap. Looks like
this issue is not easily addressed because of the lack of standards in
the perceptual rendering intent. I think there is no perfect way of
doing this mapping since there are an infinite number of source and
destination volumes. Looks like Monaco algorithms are making a better
estimation for the gamut of the Epson X600 Ultrachome printers.
It should also be noted that some of us (including me) were advocating
using a relative colorimetric rendering intent. I advocated this
because the ProfileMaker profile using perceptual was over compressing.
Relative colorimetric doesn't do the same sort of gamut compression but
just maps into the closet available points (hence the need for black
point compensation). You also lose the spectral data features
(brightener compensation) in ProfileMaker by using relative.
Description sent to Roland
The issue is fairly straight forward but as with many color issues this
is difficult to measure in exact values. It is easy to see using
ColorThink's 3D modeling function. If two profiles are created under
the same conditions, one in ProfileMaker and one in MonacoProfiler, the
gamut maps are very similar. If you then take an out of gamut image and
map (perceptual intent) displaying vectors color coded with deltaE, the
issue is evident. The out of gamut points map using the ProfileMaker
profile over compressed. The out of gamut colors have larger deltaEs
with the ProfileMaker profiles.
Enclosed are two examples created using ColorThink. You can see the
gamut maps in each with an out (part not the whole image) of gamut
image mapped into the profile gamut. The image compression is mapped
using color coded vectors. The points with large deltaEs are shown in
red, smaller in yellow, and no compression shown in green. In this case
a picture truly speaks a thousand words. The image with all the red
vectors has been created using a ProfileMaker profile. The other was
created using a MonacoProfiler profile. When looking at the resulting
prints the difference in image quality is very evident.
I hope this is a clear explanation of the problem and is helpful.
Regards,
Damon
Vector map of an image by applying a ProfileMaker profile in ColorThink.
http://f2.grp.yahoofs.com/v1/4K-pPvaoYX-
a14nPKnrF1n_lUUkwdo00lHirMZtAXgnUK2l9gsavfYzgswUx029NcxoObmlDQ36xqkMG/
ProfileMaker Profile.jpg
Vector map of an image by applying a Monaco profile in ColorThink.
http://f3.grp.yahoofs.com/v1/4K-
pPjOA94aa14nPovpu0FHUu0OAGilCQFqenJ6GsGceRudwrZGCOGpuLOu88KGk5RYte7qQImv
w96-Z/Monaco Profile.jpg
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