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Re: High resolution scanning



Hi Dick,

<< Steve's point - which is perfectly correct - is the converse. If you
arrange the optics of the film scanning system such that you use the same
number of pixels in both film gauges, then you get a higher resolution scan
in 16mm. In the specific case of Spirit, the 16mm gate uses the full 1,920
pixels of the CCD block, and so, in terms of resolving power, is actually
more than twice as good as 35mm. Super 16mm has a frame width of about 12mm,
divided by 1,920 pixels, divided by 2 for Nyquist, is up around 80 pairs per
millimetre, which is very good. >>

Just wanted to say that I think you had it right the first time.  For a given
stock, the resolution of the actual film is the same whether it is cut to
16mm or 35mm.  But the area of a 16mm frame is 25% that of a 35mm frame
(assuming both are the same aspect ratio), so the the results would be
comparable only if you shot one-quarter of the 35mm image full-frame on the
16mm film!  Generally speaking, people prefer to shoot full-frame on any size
film, so concentrating more pixels in the scanner on a smaller piece of film
will not make up for the fewer number of film grains capturing the image in
the first place.  You just end up with a nicer scan of a grainier, lower
resolution image.

I can understand why Philips elected to do it their way: the amount of data
per frame stays the same in either film gage, which simplifies the data
processing and handling hardware in many ways.  Resolution Independence for
video isn't exactly here yet, though I'm sure we'll hear plenty about it at
NAB in a few weeks!  The Kodak Cineon Gensis, by comparison, uses only part
of its CCD sensor when scanning 16mm film, and creates correspondingly
smaller data files.  This is a defacto filtering-out of redundant data, which
is helpful in a computer environment where files don't have to be any
particular size, but they do have to be stored, moved, and processed.

Christopher Bacon
DuArt Video


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