Digital BW, The Print

Put another way, colour management has developed sophisticated systems for
dealing with out-of-gamut colours.  ICC-based colour management engines know
the gamut limitations of the printer/paper combination and can deal with out
of gamut colours (eg a very dark black) according to the selected method.  I
am not even sure whether a B&W RIP such as QTR "knows" the gamut of the
selected printer/paper combination but this is measured and recorded in the
linearization process and entered into the curve descriptor file.  The
question then becomes how does the RIP map the image pixels to the output.
I really do think that this area requires some extra thought from people far
brighter than me - I am just an unemployed investment banker who used to
read his reports on an LCD screen in a sunny corner office ;-)


> From: Steve Kale <stevekale@...>

> 
> But it also leads to the discussion I began with Roy awhile back as to how
> B&W "gamut compression" should be handled.  The classic complaint is that
> (non soft-proofed) images print lighter than on screen.  A result of the
> lower dMax of the ink/paper and a shift of the tonal composition of the
> image by the RIP.  I am no expert in this area (and may be talking through a
> hole in my head) but it seems to me that linearisation provides a distorted
> smoothed compression into the tighter gamut (higher dMin, lower dMax) and
> every pixel in an image gets shifted - except maybe the midpoint.  I often
> wonder whether a clipping approach would be better (or some balance in
> between).  I question whether raising the brightness of the image overall
> (mid point may stay unchanged but the others are affected) to achieve "good
> separation in the shadows" is the right approach (presumable the opposite is
> occurring in the highlights). I find that when I soft proof an image for QTR
> output I end up applying an S curve to try to get back my overall tonal
> balance - accentuating the near blacks and near whites.  I may be wrong but
> I suspect this is really undoing part of what was done at the linearisation
> stage.
> 
> Regards
> 
> Steve
> 
> 
> 
> 
> 
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