[filmscanners] Re: keeping the 16bit scans

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

Ed Verkaik wrote:
> I've been scanning slides on the 4000ED, correcting, then saving the
> 16bit files as my masters. It's beginning to get crowded on my h.d.  My
> reasoning for keeping 16bit rather than 8bit was because I figured if I
> had to do a little more adjusting of curves, etc. then the files would
> handle it better. Am I right?  What's the difference in likely outcome
> (quality) if I did further (minor) edits on a 16bit/110mb instead of an
> 8bit/55mb file?  Rescanning of these would require up to an hour each of
> spotting because they're older Kodachromes so it comes down to storage
> space vs risks on quality.

An old chestnut, rekindling the 8/16 debate perhaps, and
one thing Ive asked myself a thousand times. 16 bit for
curves is much better - 8 bit runs dry when working near
extremes.

I sortof laugh now, beacuse my old 16Gb drive got full
very quickly with my scans at 16 bit. I converted a lot to
8 bit .. well, they had been corrected well, and there was
little to gain from further curve manipulation!

Now, with 300 Gb available, I think "damn, I shouldve
held out" - or should I. On any roll, or shot of importance
I might bracket anyway - scanning will pull in data
variously as appropriate.

Im also drifting into the camp of "a little bit of
lossy compression = OK, and saving the 16 bit colour
info is more important" (Paul De Rocco thanks).

With JPEG/2000 compression this is a possibility,
a very imperceptible lossyness with large savings
of space + retention of 16 bits.

My practice now is one of a mixture of 8 bits
for stuff that offers little in the way of
curve manipulation, 16 bits+JPEG2000 lossy
for everything else, except the shots that
Im dumb enough to think are worth a full
scale filesize. Note that Ive still got the
original image on neg/slide - and my scanner
can be bettered, and if I ever want to sell
the image I would borrow a better scanner and
redo it!

So - a lot less space used, and a much more
pragmatic approach.

bert


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

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