[filmscanners] Re: 24bit vs more

["Rob Geraghty" <robg@wordweb.com>]

"Austin Franklin" <austin@darkroom.com> wrote:
>> Are you saying this applies when using Vuescan - especially with negs?
> That is probably how every filmscanner that you or I would
> use, works... The issue is the software (and possibly hardware), and
> how it allows you to control this...but if you can get 8 bit data, it's
> got to have it's setpoints set and tonal curves applied.  Some scanners
> do the setpoints automatically in the scanner.  Some use "profiles" to
> apply the tonal curves...

I presume what you mean by tonal curves are curves applied to the data to
correct for the behaviour of the scanner's own hardware and the behaviour of
the film (ie. a film profile).  Maybe I'm not understanding what "set
points" are.  I thought you meant black and white points but now I'm not
sure.

>> Or are you assuming the sort of interface that Nikonscan provides?
> I'm not assuming any specific interface...

Another question then - do you use Vuescan?  Because my understanding of the
original rationale behind vuescan (which has shifted a little over time) was
to get the most possible useful information out of the scan, and leave the a
lot of the contrast and tonal correction to editing later.  Maybe Ed has
changed his rationale completely over the years, but I don't recall him ever
recommending that you should do all the image tonal manipulation in Vuescan
and virtually none of it in an editor afterward.

>> OK, then I think we agree?  Other than what you mean by "raw data".
>Typically, when you get high bit data from the scanner, it's raw data.  Raw
>data specifically means the setpoints have not been set, or the tonal
curves
>applied.
>What do you think raw data means?

I would have taken raw data to mean exactly what it says - the bytes
produced by the scanner with no manipulation whatsoever, meaning you'd have
to remove the neg mask, invert and do tonal correction in an editor.

Perhaps my view of "raw" is skewed by being a programmer or using Vuescan;
whose raw files are exactly as I described above.  More importantly, the raw
data is useless to me if I want to take advantage of the scanner's IR dust
removal feature.

Rob

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