Removal of star reflections (not circular)

[rbotero]

Hello

The forum machine recommended I didn't resurrect this thread: http://pixinsight.com/forum/index.php?topic=6921.0 so posting separately...

I was taking some pictures of the field encompassing M97 and M108 last week and now that I come to process my luminance frames I think I have a large reflection from Merak in all of them! 

I have not seen this type of reflection before in any of my other shots and can only assume it arises from the star being off-field rather than included in it.  I have frames on both sides of the meridian but unfortunately the reflection sits in the same position so I cannot really extract by separating the sets of frames.

Any ideas?  Or just retake, re-centre and re-baffle....

Happy 2017 by the way!  8)

Thank you

Roberto

[chris.bailey]

You can tone it down quite a lot using DBE. Lower the smoothing factor down to 0.1 or 0.15. It does leave much of the streaking however.

Another option is so take a clone of the image and apply a Histogram Transform to it with the black point up at the 1/4 mark and the mid-tone slider at the half way mark. Now in MMT disable all but the residual of 8 layers. this gives a reasonable mask to apply to the original image. Now use curves to lower the Luminance of the masked image.

Chris

Doing the second option and then the first get me to this

[rbotero]

Thank you Chris!  Will try out your suggestions - I can claim the streaking to be IFN!! 

[rbotero]

Chris

I have to say your method works as well as one could possibly expect given the nastiness of the reflection in my original email. I have played with the histogram settings you recommend and applied the correction twice:  Clone->histogram->MMT->histogram and then once more to the resulting image.

Thank you once more.

Roberto