Archived posting to the Leica Users Group, 1997/11/15

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Subject: Re: scanning
From: "Patrick G. Sobalvarro" <pgs@sobalvarro.org>
Date: Sat, 15 Nov 1997 14:15:42 -0800

At 11:28 PM 11/13/97 -0500, FSilberman@aol.com wrote:
>Hi Jim:
>I was reading your thread on the lug on drum scans & photoshoping files. I
>bought a Nikon coolscan II scanner to do just what your taking about.
>Unfortunately, I've been using it mainly for fpo's to date. The problem is
>that when I scan in my transparencies they scan way to dark. I've tried to
>tinker with the Nikon software to no avail. When I pale the scans in
>photoshop they pixilate badly, some of the values remain dark & others get
>lighter. 

My answer may be less than entirely useful to you, because you already have
a Coolscan II.  But the problem you're experiencing is that the Coolscan II
has a small dynamic range, too small for transparencies.  The Coolscan II
is a 24-bit scanner, where the LS-1000 Supercoolscan or the Sprintscan 35+
are 36-bit scanners.  Since the dynamic range is small, the scanner can
capture either highlight detail or shadow detail -- not both.  It sounds
like the software has made the choice to capture the highlights and leave
the shadows dark.  I don't have a Coolscan II, so I don't know if you might
be able to use an exposure setting in the scanner software to tell it to go
ahead and wash out the highlights and look into the shadows.  If the driver
and hardware let you do this, then you could make two scans, one for the
highlights and one for the shadows, and combine them in a complicated way
in Photoshop.

You're probably already aware that if you use a film that has a smaller
dynamic range (is less contrasty), like a color negative film, you'll be
able to get more shadow detail in your scans.

PhotoCD's also supply 24-bit images, but the transparencies are usually
scanned with scanners that have a greater dynamic range than 24 bits.  Here
a lot depends on the operator.  A poorly-made PhotoCD from a cut-rate shop
will have poor color correction, poor exposure values, dust and fibers on
the images, and will be very frustrating for you -- you might well be able
to do better on your Coolscan II.  A well-made PhotoCD from a reputable
shop will be very good and will cost extra.

Polaroid is reputed to have the most flexible software of the consumer film
scanners.  Certainly you can perform color correction and brightness and
contrast and curves in the scanner itself with it.  I certainly recommend
it, if it's not too late for you to switch.

- -Patrick