Digital BW, The Print

Not sure why this happens but I have noticed that some grayscale images that
I convert to RGB end up with gaps in the shadow end of the luminosity
histogram immediately after conversion.  Gaps that were not there before
conversion.   My solution is to convert from grayscale to multichannel,
create two copies of the original grayscale channel, then convert from
multichannel to RGB.  If you are using any process that requires you to
convert your grayscale file to RGB and apply curves, you may want to try
this additional conversion step - especially if you have noticed any
posterization happening in the shadows.  Definitely shows up in a print of a
grayscale gradient converted to RGB with any significant curve manipulation.

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