Re: Photoshop Gamut warning vs ColorThink
Re: Photoshop Gamut warning vs ColorThink
- Subject: Re: Photoshop Gamut warning vs ColorThink
- From: Mark McCormick-Goodhart <email@hidden>
- Date: Wed, 27 Feb 2008 10:49:47 -0500
Chris, you have convinced me. After trying to figure out the best
way to describe the Gamut warning tool, I have reconsidered, and
conclude "gamut warning" is indeed an apt description of this
feature. For those who prefer "clipping limit" that seems like a
good description, too. I still believe that the Gamut warning is
apparently being calculated on the basis of about 5dE between the
source color (ie., the color after all image edits, profile mapping
intents, and BPC have been applied) and the predicted output color.
Chris, or someone at Adobe, I'd very much appreciate a better
understanding of how gamut warning calculates the comparison if you
think I'm wrong about my 5dE assessment of this tool's clipping limit
criterion.
With all due respect to those who don't find gamut warning overlays
useful in light of their ability to visualize print output via
softproofing, I agree with Chris that the gamut warning is more
useful today than ever. Why? Because many folks are moving to larger
and larger working spaces. Prophoto seems to be getting recommended
to photographers a lot, lately. Because no monitor exists that can
display the wide gamut of such a working space and worse yet, some
colors are imaginary, I find it very useful to have an overlay that
guides me to the color clipping transition of the printer output
rather than the apparent clipping that is being caused by the monitor
profile. That said, I even find it instructive to teach students
about the monitor or working space color gamut by taking the
AaI_LAB_HueSlice_Image.psd target I described in an earlier post and
choosing the appropriate working colorspace or monitor profiles to
examine. Because this LAB image file is in fact an image that can
throw the whole LAB encoded colorspace at the output device, it is
also helpful to evaluate how and where the "secret sauce" of
perceptual mapping intents quit attempting to compress colors after a
given chroma value is reached. Gamut warning very nicely locates that
transition. Softproofing alone may or may not reveal them depending
on the confounded aspects of rendering to a gamut constrained monitor.
Chris Cox wrote:
Message: 3
Date: Tue, 26 Feb 2008 18:03:07 -0800
From: Chris Cox <email@hidden>
Subject: Re: Photoshop Gamut warning vs ColorThink
To: Andrew Rodney <email@hidden>,
<email@hidden>
Message-ID: <C3EA04DB.68481Ìemail@hidden>
Content-Type: text/plain; charset="US-ASCII"
It tells you what parts of your image are out of gamut.
Otherwise, how would you know what parts of the image need to be
brought
into gamut?
A proof setup tells you how the image will look, but unless you have a
really good display AND really good eyes, you aren't likely to tell
which
areas have been clipped.
The gamut warning is probably more useful today than when it was first
implemented - now we have more accurate color transforms, and more
accurate
color data.
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