From: Ken Watson (watsok@frii.com)
Date: 12/03/02-07:45:01 AM Z
Nze,
This is also, I am sure you know, not the way most scanners work today. They
are scanning all three colors at the same time. With the filters on the chip
there is limited materials they can use for these filters as they need to
withstand several semiconductor processing steps. If one is using separated
color filters, off chip, you have an opportunity to select much better
filtering materials and as you say only get R,G of B because that is all the
light there is.
There is software that can eliminate the sparkles. It just needs to be
determined what the largest contrast step is allowable or always assume any
large step in intensity in a black field is noise. This is generally a
workable assumption, unless you are trying to image lint on a dark cloth.
Ken
l Message -----
From: "nze christian" <christian_nze@hotmail.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Monday, December 02, 2002 2:55 PM
Subject: Re: Scanning for greater dynamic range
> 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
> > >
> > >
> > > > >
> > >
> > >
> > > _________________________________________________________________
> > > MSN Messenger : discutez en direct avec vos amis !
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>
>
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