ImPPG and number of iterations question

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Radon86
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ImPPG and number of iterations question

Post by Radon86 »

Hi,
I came across an article on Lucy Richardson deconvolution, and how to optimise sigma and iterations. It was not for solar imaging in particular.

One question comes to mind:
1) How to find the optimal iteration number when you are not sure of Sigma value to apply ?

I suppose you have to find sigma using a high iteraion number and then reduce sigma. You could use a sensible search sequence that involves finding the range of sigma which is optimal.

Then vary the iterations. This supposes you can reset the deconvolution results in ImPPG without applying to the image (which you can do).

Thanks.
Magnus


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Re: ImPPG and number of iterations question

Post by Montana »

It's a bit like the chicken and the egg Magnus, trial and error. I have always wondered that there must be a mathematical way of working it out. This is why I hated AstraImage as the real time tuning was so slow it was impossible to experiment. At least with ImPPG you can try various combinations quickly and see what impact iteration vs size does.

Alexandra


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Re: ImPPG and number of iterations question

Post by Radon86 »

Hi Alexandra,

I have also downloaded Astraimage recently for its "deconvolution"" abilities. Still no where near able to use it properly.

There is AstroImageJ (not for deconvolution) and Astrosurface (wavelets and Lucy Richardson) deconvolution.
There is so many, it is easy to get things mixed up in a short space of time.

I think you have answered the iteration and sigma question in the past. I will keep on testing and seeing if there is a possible solution to sigma/iteration in LR Decon.

Thanks.
Magnus


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Re: ImPPG and number of iterations question

Post by nicspenceryork »

This is a really interesting question which I have been wondering about too.
Sometimes when my seeing hasn't been great for CaK and I can't stack as many frames, I get a 'broccoli with dots' effect (best way I can describe it!). I tried dropping iterations to 30 which improved the appearance but in turn sacrifices bringing out as many of the details.
I'll watch this post with interest and in the mean time, like you, I'll keep experimenting,
Nic


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Re: ImPPG and number of iterations question

Post by Rob63 »

nicspenceryork wrote: Sun Apr 07, 2024 6:02 am This is a really interesting question which I have been wondering about too.
Sometimes when my seeing hasn't been great for CaK and I can't stack as many frames, I get a 'broccoli with dots' effect (best way I can describe it!). I tried dropping iterations to 30 which improved the appearance but in turn sacrifices bringing out as many of the details.
I'll watch this post with interest and in the mean time, like you, I'll keep experimenting,
Nic
If you are stacking low numbers of frames (I typically go for 20-30 in Ca-K) you really don't need much, if any, deconvolution.
I will often just use unsharp mask, and maybe 1 to 5 iterations of LR Deconv


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