Allo Roger,
Thanks for your response
So , am I right in assuming
that if both Colorthiink and Adobe are using the same table to infer the gamut
range of the output profile then there would be no explanation for any
discrepancy between them?
Strangely Photoshop seems to know an output profile colour
is out of gamut even though gamut warning does not indicate it as such, since
the difference is being picked up by soft proofing but not by the gamut warning.
I have made a file of patches of these, low- flying
spy" colours which pass under the radar of gamut warning and they seem to share
another strange anomaly. If you use
the colour-picker to fill the foreground box with one of these spy colours while a
file in its RGB workspace is active, and then activate a file already converted
to the output profile in question , the foreground colour turns black .
Personally what I find
astonishing is how such fundamentally crucial information could be at the mercy
of such an imprecise tool . I mean frankly, what is colour management for if not to
properly administer the transition from data to ink?
PS
I am sorry I missed the debate
on this, Ill go back through the archives.
Thanks again
Eugene
Appert
Montreal, Canada
----- Original Message -----
Sent: Saturday, October 14, 2006 4:57
PM
Subject: Re: gamut warning failure
Eugene,
Gamut warning is
a sensitive issue. I'm not privy to the internals of how
Photoshop's gamut
warning does it but I know it is a controversial subject
whenever the
subject comes back for discussion.
The way I understand it, the gamut
of a device is inferred from a profile
device to Lab table. To my
knowledge, that's usually the table used by
ColorThink and other 3D viewers
to draw the shape of the device gamut in
OpenGL or other 3D visualization
scheme.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
>
I am wondering if anyone understands the mechanics behind gamut warning
in
> Photoshop. It¹s a given that the tool is unreliable for displaying
out of
> gamut colours but I am forced to use it since the students I
teach have no
> alternatives for targeting files for output. I
have been making sample files
> of colours ( within the brightness range
of the output profile) that change
> visibly on the screen while soft
proofing with relative and no BPC, which
> gamut warning does not show
as out of gamut. Inevitably Colorthink shows
> these colours as
being out of gamut for the given output profile. But I
> cannot
seem to find a logic that would enable me to predict when gamut
warning
> is likely to fail. It seems perfectly arbitrary. There
doesn¹t seem to be any
> common hue, brightness or saturation placement
that increases the possibly of
> gamut warning failure.
>
> Is it possible that this is linked to profile quality or is it just
an
> inherent flaw in gamut warning?
>
> I have
noticed that many of the out of gamut colours that gamut warning will
>
not show are also colours that are out of the monitor range and I wondered
if
> there could be a connection.
>
> Thanks for any
input
>
>
>
> Eugene
Appert
> Montreal, Canada