Digital BW, The Print

I think I would rather have all values between 80-100 be 80.  At least the
80 value will be 80 and a 90 be at least as black as possible.  (And all
units from 0 to 10 will be as white as possible.)  There will of course be
some loss of shadow detail but this is simply because it is beyond the
rendition ability of the printer, ink and paper combination (in the same way
that it can¹t produce a 5 because the paper isn¹t white enough).  Better
this than a complete remap of the tone of the image and in effect lightening
the whole image so that we retrieve the shadow (and highlight) detail at the
margin (which we likely reverse with a curve at the time of proofing).  Put
another way, if we are happy with 80 as a deep enough black then we will not
be too worried that a 90 only prints at 80.  (Of course the goal is to find
an ink and paper combination that is capable of expanding my 10 to 80 space
to a perfect 0 to 100.)  I suspect this is all much more of an issue in B&W
with its simpler colour space, particularly when we typically drive for
contrast with deep blacks offset with strong highlights.  A flat grey image
is exactly what we don¹t want.  In a colour image there is a lot more going
on and the various ways of dealing with out-of-gamut colours are more
appropriate.   I agree that there should be good separation between 10 and
80 so that we get a good ability to print in-gamut shades of grey.  The
question is what happens at either end and the impact on the image of
dealing with this.  As for units, I guess I am thinking of RGB values or any
other means of measuring a grey scale space.  I used 0 to 100 as a simple
description.  I guess in RGB these would be equal R, G and B values from 0
to 255. 


From: "Roy Harrington" <roy@...>

Steve,

I think you are right that there is a "gamut compression" going on.  But
I think there's a basic fitting of one gamut into another happening no
matter what.  I'm not even sure how you'd compare a 75 gray in a file, a 75=

gray on the screen and a 75 gray on paper in absolute terms.  What are
the units?

Although I can see you point in your 10 to 80 example, I'm not to sure
trying to do things "absolute" is great either.  Wouldn't you result in all=

the values from 80 to 100 being mapped to the same max 80 density?
Maintaining the best separation you can throughout seems like a better
alternative.   This is analogous to the color rendering -- using Perceptual=

rather than Absolute Colormetric.





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