Datacolor User to User Support Group.

>the last few days i have been frustrated with a continuing problem with
>my printer and error messages. in the middle of error messages i was
>able to get some prints out successfully but with color disasters. just
>now i have finally gotten the printer working without errors but the
>colors remain off from the intended soft proof appearing in Photoshop.
>i had one test print prove to resemble the soft proof this morning but
>all subsequent tests have resulted in yellowish prints. after three of
>these i remembered others here commenting on the same thing. it is a
>clear yellow cast across the entire image. i am baffled at how tests on
>the same paper and inks (MIS) could result in this amount of variance
>for the day. i must note that i also had a red cast this morning. i
>finally re-profiled and made a fresh profile with fine results, but now
>it appears the profile has corrupted again. it is strange to say the
>least. i have noticed 'drift' in the profiles i have made since i
>started using PFP. all the profiles i made, from plain paper to
>enhanced matte, for both my printers (7600 and C84) now generate
>inaccurate prints from the soft proof, something that was fine at the
>time i made the original profiles.
>
>not sure what is going on.

Ghi:

It has to be your printer. Profiles don't corrupt, or change, after you've
build them. If you print through a given profile one day, and then see
color shifts, yellowish casts, red casts, etc. when you print through the
same profile another day (assuming that all other things are equal: that
you're using the same driver settings when you print through the profile);
then your printer is behaving inconsistently.

And if your printer is inconsistent, then things are never going to be
stable. Let's say that you wake up this morning, everything was printing
fine yesteray, but today: there's a red cast. (Note: this shouldn't happen!
assuming that you haven't touched the printer, changed the inks, switched
to a different batch of the same paper). But let's say that it does, for
whatever reason.

You reprofile, the new profile now makes up for the red cast, but the next
day, or later in the afternoon, the printer shifts again, using profile #2.
You could keep trying to catch up with the printer forever.

The key here is making sure that a) you're using the same profile, and b)
all of the driver settings you're using to print through the profile are
consistent. If they are: then the printer should be stable, as long as you
don't switch inks or papers.

If the printer isn't stable, then you can always "fix" it by reprofiling
(which is a good side-effect of having PFP); but instability would mean that
the color would keep going "off", and you'd have to catch this and then profile
again (a bad situation, which shouldn't be happening).

There should not be that amount of variance, and if there is, then something
is wrong with the printer or inks.

-- 
David Miller
Senior Software Developer, Digital Color Solutions
ColorVision