Re: [APML] Couple of Wide-Angle shots on Konica Centuria 400 (andscanner noise suggestion)

["Carlos Milovic F." <cmilovic@yahoo.es>]

> Jerry L seems pretty well versed on scanner
> esoterica, I wonder if he might
> jump in here if he knows anything about scanner
> internal bias subtraction?

Hi all

I have the feeling that at least the SS4000 does a
dark frame substraction, so, if the bias is
independent of time, and it is not bias corrected, you
have both processes at the same time. Anyway, I think
that we don't need to worry too much about them. The
noise from the scanner is charactericed by a higher
frecuency than the film's, so, using a
multirresolution analisys like wavelets you can
isolate it and reduce it, without affecting the
information in a significative way. I'd better take
care of taking true raw scans, save them at the higher
bit deph as possible, multiscan the originals and
average them, and later work with them with the best
software we can.

BTW, I think that we may use a non exposed frame to
perform a bias "film" substraction. It might substract
the film base and any residual bias from the scanner.


=====
Regards,

Carlos Milovic F.
-------------------------
Astro & Photo - CMF
http://www.astrophoto.vze.com
-------------------------
Visita "AstroFoto", el foro de astrofotografía en español
http://espanol.groups.yahoo.com/group/astrofoto


		
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