[filmscanners] Re: 8 bit versus 16

["Robert Logan" <bert_logan@btopenworld.com>]

Austin Franklin wrote:
> It really depends on if you are talking color or B&W.  For B&W, there is no
> question, you need to use 16 bits for doing all but a minimum tonal curve
> adjustment, but for color, for most applications you won't see any
> difference using 8 bit data or 16 bit data.

Have to agree on the B&W front - 16 bit is essential -
after scanning in a roll of old FP from some years ago
and I forgot to set to 16 bit - I got a shock when
doing curves - boom - highlights would just explode :)

As for 16 bit, I cant agree. If you take a picture of
a heavily red scene - autumnal sunsets and leaves etc
are coming up for example, then your film is going to
be using a much larger range of 'reds' than 8 bits
can accomodate. Dithering with other colours will occur
with the 8 bit scan to make up the difference in the
digital scan vs the analogue film. Once you start
messing with the curves on this, it will make matters
worse. Having 16 bits of red to work with will leave
much broader scope for manouvering in curves. Its
analogous to the black and white issue above.

8 bits is only 256 possible reds/greens/blues. Theres
no way I would rely on this for editing, although the
final destination (print) might make no use of all that
info.

--
Linux - reaches the parts that other beers fail to reach.

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