[filmscanners] Re: Minolta DiMage Scan Dual III - bit depth

["" <anthony@ohalloran.co.uk>]

> I  briefly compared 8 and 16 bit output, as well as 8x multisampling to
> reduce noise. My test image did not have subtle tonal gradients, so the
> difference between the 8 and 16 bit output was nominal.

The first time i did a 16 bit scan i was disappointed that i couldn't
see any difference from an 8 bit. 16 bit scanning is only really useful
if
1) you are going to do some drastic stretching of the curves, or 2) you
wish to scan a neg using the entire dynamical range of the scanner and
cropping the histogram at a later date.
Remember 8bit gives you 256 levels per channel (2x2x2x2x2x2x2x2=256)
which is more than the eye can detect.
16 bit gives 65536 levels per channel
(2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2=65536).
This means if you scan in 16 bit at full dynamical range, even if your
histogram looks like this ____________________/\____________________
 you still have a good range of tones after cropping it.

Anthony

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