converting between col profiles and working space

I use adobe rgb (1998) as my working space.
I converted (image>mode>convert to) many files to a col profile dedicated
for a continuous tone commercial lab printer (agfa d-lab/agfa sensatis
paper).
Unfortunately, I did not do this conversion on a duplicate and have not
retained the original.
Am I correct in assuming that because the lab's col profile is a smaller
gamut than my working space, there is no point in converting back from their
profile to my working space? And for best image quality I should start again
(scan) with those files in my working space.?
And if I want to use their updated profile I should just convert directly
from their old profile to their new one?
Frank

 

In case you do edit those images it is beneficial to convert to a
colorimetric RGB working-space. The lab's profile is a 3d look-up type
profile, editing images in such profile spaces will usually give some
nasty surprises.

Converting them back of course will not help to what was lost in the
first conversion.

Yes.

Timo Autiokari http://www.aim-dtp.net