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[filmscanners] RE: scanner dmax discussion


> This is true in a philosophical and theoretical sense, but I believe we
> would have a difficult time pointing to any scanner which has an
> electronic
> circuit doing anything explicit with samples of an identifiable spatial
> frequency function.

Fact is, it takes a certain sensor element pitch to replicate a particular
spatial frequency, and that is what a scanner does.  It may simply be a
"spec" to you, but it IS recreating spatial frequencies.

> The scanner does simplistic electronic time sampling of the CCD's data
> stream,

Correct, and I've not said anything different...

> which is only a set of x values, row by row, in fixed
> format for the
> frame.

Row by row, fixed format or not does not effect how the CCD/AFE/AD
work...the AFE/AD don't know a thing about anything except voltage...

> The output file presented to the coumputer doesn't "know"
> or "say" it
> is an image: it is just an ordered set of pixel values with at most some
> simple pixel-by-pixel corrections.

Exactly, and this was my point that the scanner doesn't know squat about
"film noise", which you've yet to explain...

> As I mentioned to Austin, we're way off the deep end on this
> topic and need
> a way to get back to clear relevance for scanners and their
> explicit active
> functions.

The WHOLE subject was number of bits that the A/D is in a scanner, and how
that is determined.  I've stated how it's done, you've disagreed.  OK, so
here is an exercise for you.  The CCD has an output voltage of 0-2.5V, with
a noise of .001V.  How many bits do you need to "sample" the data with such
that the entire dynamic range available from the CCD data is captured, and



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