[Leica] Shadow noise in scans

[dorysrus at mindspring.com (Don Dory)]

Peter,
As a follow up below is a re-crop of your original scan from the store:
http://gallery.leica-users.org/On-the-road/slide_13

Their machine did not put any noise in the image, however, they did not
bother providing much information in the low values as you can see in
the little girls hair.  Obviously, there is a middle ground where very
little noise is present but most values are present as well.

Don
dorysrus@mindspring.com

-----Original Message-----
From: lug-bounces+dorysrus=mindspring.com@leica-users.org
[mailto:lug-bounces+dorysrus=mindspring.com@leica-users.org] On Behalf
Of Peter Klein
Sent: Sunday, August 15, 2004 1:41 AM
To: lug@leica-users.org; leica@freelists.org
Subject: [Leica] Shadow noise in scans

Folks:  I frequently encounter shadow noise in my scans. I can usually
work 
around it, but I'm wondering if there is something I can do--perhaps
while 
scanning--to minimize it.

Have a look at this:
http://users.2alpha.com/~pklein/temp/noise.jpg

This picture was taken with an M6TTL and CV 50/1.5 Nokton, on Kodak
T400CN 
rated 400.  It was taken in a dim reception hall, but the subjects were 
illuminated by a shaft of light from some nearby large windows, and I 
exposed for them, not the background.  The scanner is a Canon FS-4000,
run 
at 4000 dpi and driven by VueScan.  I scan to 16 bit TIFF, and use
Picture 
Window Pro in 16 bit mode for my editing.  The various versions of the 
picture are shown at 1/3 actual pixels.

The leftmost image is of the scan pretty much out of the scanner (I'd 
spotted and cropped, but that's all).  You can see the noise in the
darkest 
areas.  This is the kind of noise I am often plagued with.  It tends to 
happen more often in available light pictures than well-lit outdoor 
shots.  It doesn't show much on a 5x7 quadtone print, but is quite 
prominent on an 8x10.  And if I get the same negative printed in a wet 
darkroom, the noise isn't there.

The center image is what I ended up with after curves, contrast, and 
sharpening (the latter using a mask so only the people were sharpened,
not 
the surrounding area).  I've dropped the background to nearly jet-black,

but there are still lots of noise speckles.  And I've lost some
gradation 
in the girl's hair.

The righthand image has been noise-filtered with NeatImage before
curves, 
etc.  I used it sparingly so it wouldn't soften or "plasticize" the
image 
too much.  It's helped, but the noise still shows up--more in a print
that 
on the screen.  I've found that most of the time, when I use NeatImage
or 
Picture Window's Despeckle feature, I can only get rid of some of the
noise 
before the image gets messed up.

What might I try to get rid of this noise?  Is there anything can I do
to 
minimize it during the scan?  I've tried the multiple exposure feature
in 
VueScan, and it doesn't really help with this type of noise.

BTW, here's the whole picture.  This one is a reduction of the Costco CD

Jpeg I got when the film was developed.  They went way dark, so you see
no 
shadow noise (or detail).
http://users.2alpha.com/~pklein/JonAntionWedding/Show/JonAntionWedding/s
lide_13.jpg

Thanks,
--Peter Klein
Seattle, WA

_______________________________________________
Leica Users Group.
See http://leica-users.org/mailman/listinfo/lug for more information