Deconvolution strategies

[vicent_peris]

Hi,

Have you tried to apply more iterations with the process with the synthetic PSF generated by DPSF? In my experience it needs more iterations but usually works pretty well. Try with 100 - 200... Of course, having a PSF with a larger StdDev you'll have more ringing... I try to correct them partially with the global options and use the maks to correct the stronger ones.


Regards,
V.

[ManuelJ]

Hi,

Have you tried to apply more iterations with the process with the synthetic PSF generated by DPSF? In my experience it needs more iterations but usually works pretty well. Try with 100 - 200... Of course, having a PSF with a larger StdDev you'll have more ringing... I try to correct them partially with the global options and use the maks to correct the stronger ones.


Regards,
V.

Yes, maybe I have to improve my masks. I don't like the effects of the global options on the data, it tends to create ringing artifacts. One small touch is ok, but if your black halos are quite evident, global options is not the only way to go.

Regards,
Manuel.

[viktorbravo]

Thanks for a great tutorial Manuel.  I agree that I like the image better with your PSF.  With the synthetic PSF the image looks, well, more synthetic.

I found that generating the ideal masks are quite time consuming for me.  However with a little more practice I should get quicker at it.

Vince

[niteman1946]

Hi Manuel,

This is a good tutorial and thanks for posting it.

With this guide I was able to produce quality images using Decon for the first time.

Appreciate your good effort.

Mark

[ManuelJ]

I'm glad that this is useful for you, guys.

[Lex]

Yep indeed, huge thanks again! You're the man Manuel  8)

[Raymond]

Hi Manuel
Thanks a lot for this very instructive tutorial.
I tried your workflow for one of my images and some questions appeared:
1. If during deconvolution the message appears 'local divergence at iteration ...', does this mean that some parameters have to be changed, or is this not fatal for the processing?
2. After deconvolution, small dark rings appear around some stars. With 'global dark = 0.0030' these dark rings disappeared. Is this the correct approach?
3. The background is protected by a mask. But in my image, the appearance of the background changes slightly comparing before/after deconvolution. Using the script Noise Evaluation, the noise raises by about 2%. Is this normal, or is the applied mask not correct?

[ManuelJ]

Hi Manuel
Thanks a lot for this very instructive tutorial.
I tried your workflow for one of my images and some questions appeared:
1. If during deconvolution the message appears 'local divergence at iteration ...', does this mean that some parameters have to be changed, or is this not fatal for the processing?
2. After deconvolution, small dark rings appear around some stars. With 'global dark = 0.0030' these dark rings disappeared. Is this the correct approach?
3. The background is protected by a mask. But in my image, the appearance of the background changes slightly comparing before/after deconvolution. Using the script Noise Evaluation, the noise raises by about 2%. Is this normal, or is the applied mask not correct?

Hi,

1. No problem
2. There is two ways, lower the stddev or correcting with global dark, experiment and see what looks best to you. If find always better to trick the stddev.
3. Try to protect the background better. Apply a shadows cut in the mask histogram.

Regards,
Manuel.

[Raymond]

Manuel, thanks for your explanations!

[Silvercup]

There are a few tricks that we must take into account.

If I have time I'll try to explain, making an extensive tutorial about deconvolution for both planetary and deep sky images.

Silvercup

[mmirot]

Nice tutorial

Should not the high SNR mask be named low SNR? It is masking/protecting the the low SNR background.

Perhaps sampling the center 50 percent using the DPSF would give better results. The information you want improve is often central and less effect by off axis effects. The psf model might be skewed depending on the optics leading to bloated model

Max

[Geoff]

Hola Manuel
Let me see if I have this correct.  When you say "Protect the original image with the mask", the mask you are referring to is the high SNR mask.  The star mask is used only in the local deringing panel and is never explicitly applied to the image.
Thanks for the tutorial; it brings a lot of things together.
Geoff

[ManuelJ]

Hola Manuel
Let me see if I have this correct.  When you say "Protect the original image with the mask", the mask you are referring to is the high SNR mask.  The star mask is used only in the local deringing panel and is never explicitly applied to the image.
Thanks for the tutorial; it brings a lot of things together.
Geoff

You're right!.

Regards,
Manuel.

[gvanhau]

Thanks Manuel

Al least for me, this tutorial was very usefull.

Regards
Geert

[niteman1946]

Thanks again Manuel.

I've since migrated back to Juan's method of using the synthetic PSF.  For me it appears to do no worse, and is quicker than using the manually calculated stddev.  Global Dark adjustment (usually around .005 for nebulae) has become my favorite tweek.

Notwithstanding that, you got me going in the right direction, and I routinely use Decon for all my images.

Mark