>> The reason I posted the question was that a Repro company has told me
that
they would prefer me to supply a job in RGB so they can do the conversions
but I would prefer to try out my new profiled 7600 and Best Photo Xposure
RIP to supply CMYK targeted files and proofs. <<

Hi Dominic, this sounds like a worthy goal, and you obviously want to do
this yourself. Are you saving money on the job or is this for other reasons?
Even though outsiders may not agree with all in-house decisions, these
people often know their conditions well and can do a good job in many cases
(although in this case it sounds like they are setting themself up for a
fall).


>> We have agreed to do a test where we both start with the same file and
both
supply a converted file and matchprint to a given standard. <<

As you say, it is hard to start at the same level when there are different
colour management issues in each workflow.


>> The problem I have is that I suspect a 'closed loop' situation and the
guy
has already told me he discards the tags upon opening tiffs (just works 'by
the numbers'?!?); hence the 'not colour managed' bit of my original post, I
have asked him if his production dept. has a standard RGB working space, If
they have I fear it could be sRGB. <<

Yes, it sounds like mystery meat RGB.

Sadly since there are many flavours of RGB, working by the numbers only
works if you happen to use the right profile to describe those numbers -
which may not be the case if this user has warnings turned off etc.


>> OK, I know if I can find out what his starting point is (working RGB
space)
it would be fair(er) test but we can't all be expected to second guess whats
going to happen to our files once the job has left our control. <<

Give them a LAB version of the file, if you are concerned about these
matters and you cant trust that they will give you correct info or that
things will work that way when they get the file. Sure, 8 bpc ICC LAB has
some issues - but if all you are doing is handing off a file for output
conversion and nothing more, then the insurance of Photoshop LAB may
overcome ICC colour management issues (just look for any major hue shifts in
blues, not that common but with A98 it is more possible than say ColorMatch
RGB). This will force them to convert to CMYK from a known source LAB
(Photoshop 5 and higher all use the same LAB).

Photoshop D50 ICC LAB is a standard you can rely on from one version of
Photoshop to another. Just tell the other party to either change direct to
CMYK as their very first step after opening before resaving for their output
use (or RGB in those cases of non press supply).

You too would convert from the same LAB file to keep the variables down
between your work and theirs, although since you know what the RGB is and
you do follow the tag then you may just prefer to go from RGB to CMYK and
not restrict yourself to the same conditions as the service provider, since
it sounds like you know better.

Stephen Marsh.

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