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[filmscanners] Re: Polaroid SS4000, noise,and oversampling (was: VueScan 7.5 beta 8 Available)

I think the issue is one of pragmatics.  All CCD scanner have some noise
in shadows. It appears though that some keep that noise near or below
the black point, and therefore it becomes basically moot.  Further
still, in isn't as if multipass scanning is "free".  It adds 2-3-4 or
more times the amount of time the scan takes to accomplish.  It becomes
a matter of loss/benefit ratios.

If I had a scanner which was particularly noisy in an area of the scan
that was visible, (in other words within the scanner's ability to create
meaningful gradients) then certain problematic images might be
worthwhile using these methods to improve.  BUT, if the noise was
basically near the black point floor (even if that black point was high
due to poor dynamic range) then the advantage is questionable.

The SS4000+ I have worked with exhibits minimal noise in shadows, and
none that I could see in highlights.  The green channel is minimally
noisy on the one I used.  I don't expect the advantage in image quality
would be large enough to justify running the scanner 2-4 times more per
scan, the extra time the scans take, the extra light exposure to the
film, and the risk of offset registration.

Even on the Minolta Dual II, which does have a noisy blue channel (more
about this in another posting), I got no more detail from a 4 x or long
scan.  It was slightly less noisy in the blue channel but the problem
was that the blue channel gives up well before the true black point, and
that wasn't helped by extra scans.  I probably would affect a similar
result by a simple levels output adjustment on the blue channel in
Photoshop, taking a heck of a lot less time, and less wear and tear on
the machinery.


Eric wrote:

> David:
>>You have to have noise to be able to reduce it. Noise or the lack of it is a
>>function of hardware design and in some cases profiles.
> Does a noiseless scanner exist?
> Why wouldn't oversampling and averaging help reduce hardware-caused noise?
> Hardware problems can often be somewhat fixed in software, after all.
> Eric

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