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filmscanners: Exceeding the scanner's contrast range(was: nikonscan white clipping)



PAUL GRAHAM schrieb:
 
> what would you suggest doing with a very contrasty negative, where I can't
> get both ends on the histogram at the same time? and either the highlights
> or shadows are clipped?

Hi, Paul,

my first advice would be: Use analog gain to get the *highlights* right
on the money and - just scan it :-) Negatives *very rarely* have a
contrast range to exceed the capabilities of my LS-30 (maybe one in 100)
but Nikon Scan's histogram view has a tendency to make the shadows part
of the histogram *look* as if it would clip the shadows but the
histogram of the final scan (checked with your image processing
application) will most likely be allright. If there's *real* clipping of
the shadows, you'll have to dig a little deeper. You'll need an image
processor that supports layers (most of them do). Here we go:

Make one scan with perfect highlights (shadows clipped) and another one
with perfect shadows (highlights clipped). Place the *darker* scan as
"top" layer over the "bright" scan (bottom layer). Set layer merge mode
to "subtractive" or "subtraction" (not "difference") and transparency of
the top layer to about 65 to 85 %. Flatten image - et voilà :-)

By accident, I had to do exactly that on a lioness image some days ago.
I have merged the bright, dark and combined version into a single
picture you'll find at http://schmode.net/contrasty.jpg. The histograms
of the bright and dark scan will not show blown out shadows or
highlights because the downsizing of the original file would even the
"hard" edges of the histograms a bit but you'll spot those blown out
highlights and grainy shadows by just looking at the originals.

If any more advice is needed, don't hesitate to ask again.

So long -

Ralf

-- 
My animal photo page on the WWW: http://schmode.net
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