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Darth Takahashi

Planetary Ringing

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Hi Guy's, sorry and Ladies!!! :smiley:

I need a little help here?

What causes the ringing effect around the planet?

I'm processing the AVI using Registax 6 in the usual manner, the final step being the wavelet sharpening and it is at this point that I start to get a ring around the outside of the planet and inside the disk of the planet?

Is this a stacking artefact or a problem with the wavelet sharpening?

Edited by Darth Takahashi

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Show us an image. There are few types of such rings. In old webcams they may be caused by to low gain, in old TIS camera circular artifacts due to to fast speed... :)

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Its not going to win any awards etc... but here is Jupiter from the 14/10/2012.

Imaging scope was my Mewlon M250S CR. I added the new CR baffle tube this weekend, so this is a test image to prove everything was working correctly after the installation. Collimation was rechecked but maybe a out by a hair! nothing significant. Seeing was crappy, but as I said I wanted to test the CR baffle. Imaging camera is a DMK21 and the gain was around 700 - 800 when I remember correctly :tongue:. IR pass filter fitted to the camera. It was about 05:30 in the morning so Jupiter was high in the sky.

Jup_IR_14_10_2012_065000_zps6e38ecbd.png

Its also the boring side of Jupiter but the ringing is clearly evident for all to see!!!

Jup_IR_14_10_2012_065237_zps021901de.png

With a little bit of de-noise / de-ringing but I'd sooner rather get rid of this at the capture stage if that's where the issue lies?

Edited by Darth Takahashi

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Was your gamma set at 100? I know with my DFK that ringing appeared when I had gamma in the 90s. Never get it when set at 100.

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I think it is low gain however I can't be completely sure. What was your gain setting?

Can't remember precisely where it was set? Sorry but will check next time... probably the weekend! If the clouds shift?

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Was your gamma set at 100? I know with my DFK that ringing appeared when I had gamma in the 90s. Never get it when set at 100.

Gamma was set at about 93% so you might be right!!! Why does it happen, do you know? Or is it just one of those things!!!

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Are you using heavy sharpening (Regularised Richardson-lucy or Van Cittert)?

If so the technique most use do not like a sharp contrast change (steep curve in lum/colour) - this is the same for bright stars that also cause ringing. It's better to create a mask to stop what is already sharp to prevent it going negative (the dark ringing).

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Gamma was set at about 93% so you might be right!!! Why does it happen, do you know? Or is it just one of those things!!!

Just a quirk of the imaging source cameras I think.

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Are you using heavy sharpening (Regularised Richardson-lucy or Van Cittert)?

If so the technique most use do not like a sharp contrast change (steep curve in lum/colour) - this is the same for bright stars that also cause ringing. It's better to create a mask to stop what is already sharp to prevent it going negative (the dark ringing).

No, I'm just using the factory fitted wavelets in Registax; I haven't applied any other deconvolution routines...

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I usually turn the gamma down a bit to help with focusing. On occasion when I have forgotten to put it back to 100 I have had onion rings in my stacked image. As Stuart says it is just one of those things.

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