Digital BW, The Print

> So the files that are untagged get Grayscale Gamma 2.2 *assigned* to them,
> and the ones that are presently tagged as Dot Gain 20% get *converted* to
> Grayscale Gamma 2.2?
> 
> Todd

Almost -- assign the 2.2 to the untagged file if it was supposed to be in a
2.2 space to start with.  This is may be the case since you were using Adobe
RGB. It would also be the case if you have a fresh scan which has never been
color managed.  You may then have to apply a curve in photoshop to bring it
back to a visual acceptance if it was originally adjusted for another
working space but there is not much you can do at this point to undo any
previous adjustments you made to the file.  Usually it is just safer
assigning the profile and starting over on your adjustments (if any are
needed) than converting an maybe still having to do a curves tweak.   For
the ones in a dot gain 20% space it might be better to just assign a 2.2
gamma to it then adjust back to visual acceptability with a curve rather
than *converting* to a 2.2 gamma.  Either way your are going to lose image
data so try it both ways then check the image/histogram to see if the
alteration created any gaps or a comb-like appearance.  But a simple 20% dot
gain is a smooth curve similar to a gamma curve (as opposed to some custom
dot area curves which can be very bumpy) so it may very well be okay to just
convert to the profile.  However, if you have to make further adjustments
after converting to the profile, undo that conversion and just assign the
profile and then do your curves adjustment  - you want to avoid doing both a
conversion *and* a curves adjustment.

You might want to check your Color Settings under preferences.  If you are
getting a lot of untagged files you might have a setup with a Color
Management Policy that isn't tagging.  Usually you want "preserve embedded
profiles" selected unless you are doing profile targets.  If a lot of your
files are in 20% dot gain you probably have (or had) a grayscale setup with
that as a default - change it to 2.2 instead (or 1.8 if you are going to be
using ColorMatch RGB).  The dot gain problem often crops up when you are
doing Photoshop mode changes and you haven't been too careful about setting
up the default RGB and grayscale spaces.  To avoid this you might want to
avoid using the simple Mode Change command in Photoshop - instead, always
use "convert to Profile" to change modes from RGB to Grayscale and from
Grayscale to RGB and be sure your Color Settings preferences tag all files.
So, for example, to convert to grayscale from RGB you would not just select
Image / Mode / Grayscale you would select Image / Mode / Convert to Profile
then select the 2.2 gamma grayscale space (or 1.8 or whatever).  For the
Grayscale to RGB conversion you would do the same but select Adobe RGB as
the destination space (unless you want to use Colormatch or another space).
Then, presuming you have set your color setting Color Management Policies to
"Preserve Embedded Profiles" for both RGB and Grayscale you will always have
the right profile embedded after doing conversions.

Clear as mud isn't it?

-- Dan Culbertson
so many years, so little time...