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RE: [APML] OT: Experiments with Lunar/Planetary Webcam image stacking
Hi Philip,
I can't comment on your procedure as I am still new to this game. However,
I would find it useful if you could post additional pictures of Clavius for
quality comparison: for example, one of the best raw data pictures, the
Registax-processed picutre, and the K3CCD-processed picture.
Regards,
Serge
> -----Original Message-----
> From: astro-photo-bounces@seds.org
> [mailto:astro-photo-bounces@seds.org] On Behalf Of Philip Perkins
> Sent: Sunday, November 30, 2003 12:42 PM
> To: Discussion of Film Astrophotography
> Subject: [APML] OT: Experiments with Lunar/Planetary Webcam
> image stacking
>
>
> Hello List,
>
> Over the past few months I have been experimenting (on and off) with
> techniques for registration and stacking of lunar and
> planetary webcam
> images. The two most popular tools are Registax and K3CCD.
> However after
> trying both of these using several different methods, I
> repeatedly find
> that a large number of the selected frames are quite blurred
> and definitely
> well below optimum. Has anyone else noticed this? I wonder
> if mathematics
> alone (FFT) is sufficient to accurately select the best
> frames, bearing in
> mind that such images suffer from a combination of blurring
> and non-linear
> scaling distortions?
>
> Anyway, the net result is that I have not been satisfied with
> the results
> from using these programs - it seemed that a much better
> result could be
> obtained from the available data. Of course one has the option to
> manually deselect the worst frames, but that led me to
> thoughts of a better
> technique overall. The technique I've been experimenting
> with is quite
> different - here are a couple of early results:
>
> http://www.astrocruise.com/l_clavius.htm
>
> http://www.astrocruise.com/l_alpine.htm
>
> Here are the main steps in the technique:
>
> 1) Image acquisition with K3CCD. I think this is an
> excellent program for
> acquisition, however it was not used from that point on.
>
> 2) AVI sequence editing and frame export with AVIedit. The
> only solution,
> it seemed to me, was to manually edit out all the bad frames
> from the AVI
> file. I gradually refined the selection over several passes,
> until I ended
> up with a small set of frames that were absolute premium. I
> was looking
> for not only the sharpest frames, but also those suffering from least
> scaling distortions. I then exported the good frames to
> discrete image
> files. Note that in the case of l_clavius I ended up with
> only 27 frames -
> still more than sufficient for good S/N ratio. I think I will further
> refine the l_alpine set and may end up with a similar number.
> This is
> obviously far more work than using the automatic methods in
> Registax and
> K3CCD, however if quality is paramount I don't currently see
> much alternative.
>
> 3) I then registered and stacked the images in RegiStar.
> RegiStar? - yes,
> RegiStar extracted the highlighted peaks of craters and
> treated them as
> "stars"! Thus Registar is able to very accurately align the
> images _and_
> compensate for non-linear scaling distortions within the
> image. The images
> were stacked using Average.
>
> 4) The images could easily have been presented in RGB, but for lunar
> images I felt that this had very little benefit, and I extracted the
> luminance layer in Photoshop.
>
> 5) I needed to convert the image to FITS, but MaximDL produces a FITS
> header error, so I went back into Registar for this step. I
> then converted
> the FITS image to 16 bit with MaximDL (I prefer to have
> control over this
> process in Maxim rather than in Photoshop).
>
> 6) Deconvolution was done using AIP (van Cittert) - 256
> passes. Final
> conversion back to 8 bit TIFF was done in MaximDL, with a
> final curves
> adjustment with Photoshop.
>
> I am still experimenting with planetary images. I have an
> AVI file of Mars
> taken in early September from southern France that has
> potential to produce
> a good result. Most of the above technique can apply,
> however the big
> challenge is registration - because there are no strongly highlighted
> regions, RegiStar cannot work. I can accurately align the images in
> MaximDL, however there is no means of compensating for
> scaling distortions
> within the image. I am talking with Rajiv Gupta about
> possibilities of
> extending RegiStar to cope with this kind of image.
>
> I suppose I should really be sending this to an astronomical
> webcam list -
> if anyone knows a good one and could let me know I'd be grateful.
>
> While in the middle of doing planetary imaging I produced the
> following
> "quick and dirty" image of M33 using my AP refractor and
> trusty ST-8E - I
> am sure the experts will tell me this was grossly undersampled, so
> theoretically it should not have worked... :-)
> http://www.astrocruise.com/m33.htm
>
> Regards
> --Philip
> Philip
> Perkins
> <pgp@astrocruise.com>
> Wiltshire UK & Luberon France
> http://www.astrocruise.com
>
>
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