Re: Rendering Intent for 3D plot in ColorSync Utility
Re: Rendering Intent for 3D plot in ColorSync Utility
- Subject: Re: Rendering Intent for 3D plot in ColorSync Utility
- From: david wollmann <email@hidden>
- Date: Wed, 24 Mar 2010 14:04:21 -0600
Date: Mon, 22 Mar 2010 18:30:33 -0700
From: Marco Ugolini
ColorSync uses either a Relative Colorimetric intent with BPC or (more
likely) Perceptual. Fact is that it scales both the white and black
point of
any profile respectively to absolute white and black. Obviously,
that ends
up distorting the representation of actual 3D device gamuts quite
substantially.
What's worse, the user is not given a choice of rendering intent.
In ColorThink Pro, the user can choose which intent to use among any
of the
four standard ones.
Okay, I see what you are saying and I found the popup in ColorThink
Pro. I should have remembered that popup, I was looking in all the
wrong places, thank you.
It does look like perceptual is the rendering intent used by ColorSync
Utility, the comparison between the two applications is very similar
when ColorThink Pro is set to Perceptual. It would be nice to have
that same choice in ColorSync Utility but at least now I can tell
someone which one it is.
For example if I look at US Web Coated SWOP v2 and sRGB in ColorSync
Utility one can see that there are many CMYK colors that extend
beyond
the sRGB boundary.
That's the kind of distortion caused by scaling the white and black
point,
resulting in a projection that makes the profile look way out of
proportion
to its actual size.
Well, help me understand this, doesn't Perceptual always scale the end
points when used as the rendering intent when doing a conversion from
one color space to another?
Let me use this example, I use a RIP to print to an Epson wide format
printer. I have the RIP set to use Perceptual Rendering from my
incoming RGB to the target printer profile. The work being printed is
photography and art, watercolors and illustration, no press proofing.
Perceptual gives me the best output as the RIP does not support
Relative with Black Point Compensation (BPC).
Relative only scales the black point if you have BPC and Absolute does
not have BPC but it does map or print the paper white point?
So for this scenario the Perceptual 3D plot would apply, yes?
If I was doing press proofing then Perceptual is completely useless,
because I would want Relative and Absolute, as a better comparison. Is
this correct?
Thank you,
David Wollmann
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