Re: filmscanners: AcerScanwit but also generic calibration

["Alan Tyson" <AlanTyson@bknowl.freeserve.co.uk>]

AIUI, there is no software control of *exposure* available
to the Scanwit programmer, so you're stuck with the
automatic exposure that the machine decides is appropriate
for the frame being scanned. All Vuescan (or any other
software) can do is twiddle the raw scan after scanning. So
scanning 'black' or 'white' frames would have no point,
because the scanner would still do its own thing on the real
frame.

The only place where this has proved seriously problematical
for me with my Scanwit is that it disables the suggestions
in the Vuescan Help file for getting consistency in
multi-shot panoramas and the like. You can be careful to
expose consistently in the camera, and set the orange mask
values to be identical, but the scanner will still not give
matching tones from frame to frame.

Another place where it's a handicap is in badly over or
underexposed frames, where it would be nice to experiment
with the scanning exposure to get tone in the most desired
details.

Regards,

Alan T



----- Original Message -----
From: Shough, Dean <dean.shough@lmco.com>
To: <filmscanners@halftone.co.uk>
Sent: Wednesday, April 04, 2001 1:56 PM
Subject: RE: filmscanners: AcerScanwit but also generic
calibration


> I had assumed that VueScan and other scanner software
already did black and
> white point compensation, but I think you may be right
that they do not do
> black point compensation