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CA OR likely poor processing


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So having a slight issue with what looks like CA to me although im relatively new to RGB imaging so im guessing its more likely my processing or registration.

On all my images from different nights i have a purple edge to all my red stars.

Does anyone care to have a play with my unaligned RGB?

Blue

https://drive.google.com/file/d/1qpkymSgwRuIeHtglF3LDxJmsFQFZ1bmF/view?usp=sharing

Red

https://drive.google.com/file/d/1EvQunfNEjMfsdDIubH2FS6Afrxmz7MSO/view?usp=sharing

Green

https://drive.google.com/file/d/1l_aVxTI1VR7UXS-levPsfAG2iOUeTY05/view?usp=sharing

Thanks Ken

TEST CURVES AFTER TGV.jpg

TEST_CURVES_AFTER_TGV_clone.jpg

Edited by Ken82
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1 hour ago, old_eyes said:

Haven't had a chance to look yet, but sometimes you need to nudge one of the colours a pixel to get best alignment. Easy in PS, I don't know how you do it in PI.

Yea thanks might well be this.
 

I didn’t get any error messages in pixinsight so I was assuming it had aligned well enough. Never used PS but maybe someone can have a look. 

Just  odd that the same thing happens on different nights. 

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Well, I did a straightforward StarAlignment of your R & B to the G frame, then ran ChannelCombination with your original G and the newly registered R & B images. With the resulting RGB image, I did a STF with unlinked RGB channels and transferred the exact output to HistogramTransformation to make the image non-linear. Using Curves, I then bumped up the saturation and did a slight S-curve on the RGB/K to highlight the issue in question:

gallery_298242_11004_34474.png

So, I kept post to a bare minimum and I'm seeing the same issue you're seeing.  Those stars I've zoomed in on are just left of M106 (per your image composition), so practically image center.  IMO, I don't think it's anything you did in post.  Personally, I would be a little miffed to have to deal with this on a $5K scope.

-Ara

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