From: nze christian (christian_nze@hotmail.com)
Date: 12/02/02-03:55:08 PM Z
Ken,
I used to work with multiple scan when I made confocal microscopy. The
system is about the same as in astronmy but the pmt are a little different.
But the software I woprk with,(made by Leica) use an average system to avoid
noise. even with 2 scan it can give a better result. Sure the fact is it
work best for low value, to avoid noise in the black.
In microscoopy I used to scan first the blue then the green and last the
red. each with a pmt only sensitive to this color with filters to avoid
the avoer color to pass.
Amicalement
Nzé Christian
mailto:christian_nze@hotmail.com
http://www.c-nze.com
>
>
>----- Original Message -----
>From: "nze christian" <christian_nze@hotmail.com>
>To: <alt-photo-process-l@skyway.usask.ca>
>Sent: Monday, December 02, 2002 12:20 PM
>Subject: Re: Scanning for greater dynamic range
>
>
> > Hi,
> >
> > The double scan result in a better , because the 2 scans will be
>different;
> > the noise will not happen on the same point. The sofware will do an
>average
> > which mean that when the scan give the same result for a point, the
>software
> > let them like they are but when it give different result it will make
>the
> > average of the to point. this method is used in microscopy ofr astronomy
> > where single pmt are used. They often average to 8 or 16 which mean that
> > they scan 8 16 to avoid noise. a point should always give the same
>result
> > on the 8 scan, if not it apply a function or delete the point
>considered
>as
> > pure noise.
> >
> > In our case the noise just come from the receptor, as there is no change
>in
> > the light and in the photo. so this way to work avoid to many machine
>noise.
> >
> >
> > <If you double scan you still have the same signal to noise ratio,
> > <therefore
> > <no increase in dynamic range because you are just summing together to
> > <scans
> > <with the same signal to noise ratio. Unless you have software that can
> > <detect noise and remove it one is just fooling self. As far as I know
> > <this does not exist.
> >
> > Amicalement
> >
> > Nzé Christian
> > mailto:christian_nze@hotmail.com
> > http://www.c-nze.com
> >
> >
> > > >
> >
> >
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