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Re: [APML] Re: Van Cittert Deconvolution
Mike & Juan,
I'm really enjoying all this fuss over my Plato image!
Mike, perhaps you are too modest or have too much integrity to point this
out, but a quick perusal of your website and I see that the Adaptive
Richardson-Lucy is part of your ImagesPlus software. I'm assuming this is
what you used to process my image <G>? I will definitely have to save up
for a license of this!
Juan, any plans to market your work as well?
Again, thanks to both of you for showing me how good my crummy images can
be!
-----
Frank Barrett
http://celestialwonders.com
----- Original Message -----
From: Mike Unsold <mike@mlunsold.com>
To: Discussion of Film Astrophotography <astro-photo@seds.org>
Sent: Sunday, March 16, 2003 6:15 AM
Subject: Re: [APML] Re: Van Cittert Deconvolution
> Juan,
>
> Your experimental VC method is an improvement. Some of the fine noise
> amplification
> still remains. Are you applying the same set of band-pass filters to each
> pixel at each
> iteration?
>
> The classical Richardson-Lucy algorithm does suffer from ringing and
speckle
> noise.
> Removing these defects is the goal of the improved RL algorithm. The
> improved
> version gives much better control over ringing and noise and thus allows
the
> application
> of a lot more iterations before they start to appear.
>
> Another technique that can be used to reduce the artifacts produced by a
> restoration
> methods is to blend different restored versions of the same image. For
> example,
> 60 iterations could restore the image but produce ringing around the
bright
> regions.
> 20 iteration could partially restore the image without ringing. The
maximum
> combination
> of the 60 and 20 iteration images would have the highly restored bright
> regions of the
> 60 iteration image blended with the smooth no ring dark regions of the 20
> iteration image.
>
> In the link below the left image is the result of 60 iterations, the
middle
> image had 20 iterations,
> and the right image is the maximum combination of the left and middle
image.
>
> http://www.mlunsold.com/examples/Temp/FranksPlato2.jpg
>
> Currently I have implementations of the Van Cittert, One-Step Gradient,
> classical and adaptive
> Richardson-Lucy, and maximum entropy restoration methods. I am interested
in
> extending
> each of the methods using wavelets to determine significant structure in
an
> image. An image's
> significant structure could then be used to guide the iterative
restoration
> process.
>
> Mike
>
>
> ----- Original Message -----
> From: "Juan Conejero" <skycad@ctv.es>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Saturday, March 15, 2003 10:10 PM
> Subject: [APML] Re: Van Cittert Deconvolution
>
>
> > Hi Mike,
> >
> > Very good results with that improved Richardson-Lucy.
> >
> > We are currently working on a modification to the classical Van
Cittert's
> > algorithm which greatly avoids noise amplification. Basically, we are
> > applying the idea of suppressing high-frequency layers of the image at
> each
> > iteration. This can be accomplished through wavelets, but we are having
> > quite good results with combinations of band-pass filters, which are
much
> > faster. Here is our try on the Frank Barret's image with our
experimental
> > algorithm:
> >
> >
>
http://www.pleiades-astrophoto.com/software/experiments/deconvolution/etc/Pl
> ato-VC.jpg
> >
> > Only ten iterations of our frequency-limited Van Cittert's algorithm.
The
> > PSF was a gaussian function of radius 2.0.
> > We like the Van Cittert's method because its simplicity and fast
> operation.
> > Richardson-Lucy is more prone to artifacts (at least in our experience),
> > like ringing.
> >
> > A similar mechanism of frequency layer suppression will be included in
the
> > next version of SGBNR.
> >
> > Regards,
> > ______________________________________
> > Juan Conejero, Pleiades Astrophoto
> > skycad@ctv.es
> > http://www.pleiades-astrophoto.com/en.html
> >
> > At 18:00 15/03/2003 -0500, you wrote:
> > >Hi Frank,
> > >
> > >The noise in the dark regions of your lunar image is from noise
> > >amplification
> > >by the Van Cittert deconvolution. This is a drawback with the Van
Cittert
> > >method.
> > >Other methods have been devised to mitigate noise amplification. The
> > >following
> > >image is the result of 40 iterations of an adaptive Richardson-Lucy
> > >deconvolution
> > >using a 7x7 Gaussian point spread function. This method has much better
> > >resistance
> > >to noise amplification.
> > >
> > >http://www.mlunsold.com/examples/Temp/PlatoCompare.jpg
> > >
> > >Mike
> >
> >
> > _______________________________________________
> > Astro-Photo mailing list
> > Astro-Photo@seds.org
> > http://seds.org/mailman/listinfo/astro-photo
> >
>
>
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