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[filmscanners] Re: Another grain problem



I downloaded your images to look at in Photoshop.  There are a couple of
possible reasons for what you are seeing, but they aren't grain, per say.

The main problem seems to be in the green channel and to a lesser extent
the blue.  It may be that the green channel of this scanner has poorer
dynamic range and is unable to deal with the darker areas.  The blue
channel is also a bit like this.

It could also be the way you have adjusted the gamma and black and white
points relative to the sensitivity curves of the CCD.

You might be able to fix it by trying to scan using different white and
black point positions, and then brightening or darkening with levels in
Photoshop.  Make sure you are scanning in the highest bit depth to begin
with, as this can give you a little more latitude is adjusting the
image post scan.

Lastly, you can sometimes repair or minimize this problem by adjusting
individual curves by channel.  If you can make a mask that isolates this
density step, you might be able to improve it by lightening it slightly,
but more than likely you are hitting the limitation of the scanner to
capture these darker ranges of colors, especially in the green channel.

Art


Johnny Zasada wrote:

 > Hello,
 >
 > I own an Umax Astra 4000U flatbed 1200dpi scanner w/tranny lid. The
overall
 > quality of the scans from slide film is not so bad. Unfortunately
some areas
 > of most scans appear to be kind of grainy. These are not really deep
 > shadows, so I'm not really sure it's noise, though it probably is. Any
 > variations in the settings of the Umax MagicScan software have not helped
 > with this behaviour.
 >
 > The inkjet printer, an Epson 1200, exaggerates this graininess, it
looks a
 > bit strange having such obviously digital looking areas in an
otherwise very
 > photographic looking print. This graininess or noise particularly
likes to
 > show up in shadow areas of skintones and hair, which is frustrating
for me
 > since I mainly photograph people and portraits, and this really
degrades my
 > digital output.
 >
 > I have made up a page with two scans and magnified areas to
illustrate the
 > problem at http://www.geocities.com/johnny_zasada.
 >
 > I'd be glad to hear from you if this really is noise or am I doing
something
 > wrong. Are there any tricks to get rid of this?
 >
 > Would the Epson 2450 be an improvement, or does it have the same
problems?
 > Most reviews I've read were from landscape photographers.
 >
 > Thanks in advance
 >
 > Johnny
 >
 >


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