Pixinsight Help

[Scooot]

I've taken about 200 subs and stacked them in pixinsight with drizzle data. Below is an auto stretch after using Dynamic Background extraction on it. My polar alignment was out on the star adventurer so I had quite a bit of drift whilst imaging, so I think this is why I have the stronger signal in the centre of the image. Does anyone know if there is anything I can do to recover the image so I can use the whole fov or do I just crop off the edges? Preferably using pixinsight. All help welcome  

[RSM]

Hi, this looks like a very regular shape, not at all like the edge effects I get from overlaying subs which are not perfectly aligned. Have you tried running a second DBE, setting the sample points just on the outer section to see if you can balance the background across the whole image? Not sure whether that would work but I'd give it a try. Nice image by the way. 

Richard

[Scooot]

23 minutes ago, RSM said:

Hi, this looks like a very regular shape, not at all like the edge effects I get from overlaying subs which are not perfectly aligned. Have you tried running a second DBE, setting the sample points just on the outer section to see if you can balance the background across the whole image? Not sure whether that would work but I'd give it a try. Nice image by the way. 

Richard

Thanks for the suggestion, I've just tried that but it looks almost the same. It's encouraging to know it's probably not the overlaying of the subs though.

[Jokehoba]

Do you see this effect on the original drizzle image? Or on the basic stack (before drizzle)? Did you really have that much drift?

Sorry for the questions...

[Scooot]

8 minutes ago, Jokehoba said:

Do you see this effect on the original drizzle image? Or on the basic stack (before drizzle)? Did you really have that much drift?

Sorry for the questions...

On the drizzle image, (behind it in the screenshot) it's not visible, just a uniform red background. However when I stacked it with imageintegration before using the drizzle integration it was very visible on the resulting stack. 

I did have a lot of drift but I also repositioned the camera a couple of times and as I couldn't see the galaxy in the live view it was difficult centering it. So I probably had about three sets, with three lots of resulting drift. Some of the original subs do seem to match the shape.

[wimvb]

I would just crop the image. DBE and ABE are meant to correct gradients, i.e. smooth variations. They're not meant to correct these kind of step structures.

A more creative option is to mask the right edge. Then apply CanonBandingReduction.

Next, remove the mask and rotate the image 90 degrees. Then apply CBR once more, without mask. Rotate the image back.

With some luck, and carefull masking, you may be able to reduce the effect. I doubt if it will completely remove it.

Good luck

[Scooot]

3 minutes ago, wimvb said:

I would just crop the image. DBE and ABE are meant to correct gradients, i.e. smooth variations. They're not meant to correct these kind of step structures.

A more creative option is to mask the right edge. Then apply CanonBandingReduction.

Next, remove the mask and rotate the image 90 degrees. Then apply CBR once more, without mask. Rotate the image back.

With some luck, and carefull masking, you may be able to reduce the effect. I doubt if it will completely remove it.

Good luck

Thank you, I'll see what I can do. It's a bit annoying the gradient goes right through the centre of M110 but hey ho, live and learn  

[MattJenko]

Hi Richard,

You can also try different integration settings to handle out of shot areas of the image as I am guessing you have a lot of black spaces in the registered images.

One other option is to choose a different registration image if you are not choosing the middle sub of the 200.

Also, you could look at the mosaic aspect of registration, so it will not simply black out areas and then combine, but this will be fiddly, but you could try it out, say do the first 100 as one image, second 100 as another and then mosaic them together using StarAlignment/GradientMergeMosaic.

Cheers

Matt

[MattJenko]

Also, why drizzle? Drizzle works with undersampled images (which you probably have) with dithering, so unless you have a natural massive dither because of PA based drift on the StarAdventurer, I am not sure what drizzle will get you, apart from a very hot CPU.

[Rush]

Richard,

Like Matt says, redo without drizzle and spliitt into probably 4@50frames.

Try doing the BG neutralisation  bvor DBE.

cheers

Rush

[Scooot]

Thanks Matt & Rush.

I used drizzle because I followed a tutorial for the stacking bit  interested to know whether I should for something like this, I'm still very much a learner.

 I decided to take the easy option in the end and crop the edges. Next time I'll polar align properly.

[wimvb]

Turned out very nice.

[Gina]

Yes indeed, lovely

[Rush]

Wow,nice Image.

thanx 4 sharing

CS

 

 

[RSM]

Yes, nice image in the end.