Processing Artifacts

[lensman57]

Hi,

I have noticed that during the processing of the image of the planets in particular Jupiter I usually end up with some banding ( Ringing???) along the edge of the planet in particular if I have used pre processing such as Pipp , has anyone else encountered this and how would you advise to avoid this?

Regards,

A.G

[Davey-T]

Can you post a picture ?

Dave

[long_arms]

I used to get the onion rings when I was dabbling with a cheap asda webcam.

Became apparent during wavelets.

I remember hearing that its because the gain was set too low.

Dan

[cgarry]

Hi,

I have noticed that during the processing of the image of the planets in particular Jupiter I usually end up with some banding ( Ringing???) along the edge of the planet in particular if I have used pre processing such as Pipp , has anyone else encountered this and how would you advise to avoid this?

Regards,

A.G

Hi,

As already said an example image will help.

But a few questions:

What camera are you using?

What frame rate do you capture at?

What stacking software are you using?

What processing are you getting PIPP to do?

There are a few causes of onion rings in planetary imaging, which is what I think you are describing. One cause that springs to mind is not having enough signal in the first place and trying to correct this by stretching the histogram during processing. I am not sure how PIPP could make this worse though.

Cheers,

Chris

[lensman57]

Hi,

As already said an example image will help.

But a few questions:

What camera are you using?

What frame rate do you capture at?

What stacking software are you using?

What processing are you getting PIPP to do?

There are a few causes of onion rings in planetary imaging, which is what I think you are describing. One cause that springs to mind is not having enough signal in the first place and trying to correct this by stretching the histogram during processing. I am not sure how PIPP could make this worse though.

Cheers,

Chris

Hi,

Sorry for not posting the photo, I think you are right about not having enough gain, I also seem not to have enough frames for stacking, the thumbnail is about 450 frames I think.The scope is SW 127 MAK, the camera is Opticstar 75c and the capture was processed in PiPP, Autostakert and wavelets in Registax6 , I have over done the wavelets to demonstrate the problem.

Many thanks for your replies and advice.

[cgarry]

Hi,

I assume you are referring to the circular banding, not the vertical lines that look to be related to the sensor's bayer mask.

I am not familiar with the Opticstar 75c camera, but my general advice would be to set your exposure and gain to get a decent histogram (at least 60%) and to try set the colour balance so that the R, G and B levels are close.

What processing is PIPP doing exactly? Colour debayering? Quality selection? Or just centring and cropping.

My initial thoughts are that the ringing artefact is present in your raw frames and if you are using PIPP for quality selection, the frames with the most ringing would actually register as a having a higher local contrast value and be rated higher by quality. Actually I would have thought that most quality selection algorithms would mistake the ringing for surface detail and select these frames for stacking so I don't know why this problem would be worse with PIPP doing the selection.

If you are not using PIPP for quality selection then I have no idea how it could affect the ringing in the stacked and sharpened image.

Cheers,

Chris

[lensman57]

Hi,

I assume you are referring to the circular banding, not the vertical lines that look to be related to the sensor's bayer mask.

I am not familiar with the Opticstar 75c camera, but my general advice would be to set your exposure and gain to get a decent histogram (at least 60%) and to try set the colour balance so that the R, G and B levels are close.

What processing is PIPP doing exactly? Colour debayering? Quality selection? Or just centring and cropping.

My initial thoughts are that the ringing artefact is present in your raw frames and if you are using PIPP for quality selection, the frames with the most ringing would actually register as a having a higher local contrast value and be rated higher by quality. Actually I would have thought that most quality selection algorithms would mistake the ringing for surface detail and select these frames for stacking so I don't know why this problem would be worse with PIPP doing the selection.

If you are not using PIPP for quality selection then I have no idea how it could affect the ringing in the stacked and sharpened image.

Cheers,

Chris

Hi Chris,

I just put the file through PIPP and check planetary, I then check the quality control box and set the image size to about 360~450 and process the image, I just leave the debayer at default because I don't know anything about it. I seem to suffer a lot less of these rings if I process the file in RegiStax 6 but as I have now been taking over 2000 ~ 3000 frames to getrid of the noise, RegiStax can take a very long time processing and at times freezes up. I am now trying to use SharpCap to capture the files as the software bundled with the camera is very primitive, etAmCap, so there is no provision for checking the histogram, the camera is quite sensitve to a limit where noise just becomes too much, ie: if I wanted to use my ED 2.5X barlow on the camera and the 127 MAK, for Saturn I need to set the exposure about 300ms and push the gain about 80% way up to get a reasonable exposure, I attach another thmbnail with just a little over processing but done totally in RegiStax.

Many thanks for your help and advice.

Regards,

A.G

Jupiter 30.3.tif