M81/M82 Galaxies and IFN Processing- How to process the IFN and the Galaxies Separately

Mark Eastman

I went to a Death Valley SQM 21.97 site on a new moon and got 6 hours of really good data on M81/M82 which showed substantial IFN. I'm looking for a workflow that shows how to process the IFN in a way that does not "blow out" the galaxies. I have PixInsight, BXT, NXT, SXT and I understand how make, blur, modify, invert masks made from RangeSelection, GAME etc. My first attempt is reasonable but could be better with a better understanding of how to process the IFN and Galaxies separately

https://app.astrobin.com/i/wnf3bp

BlockHead

I did write you an e-mail:

Yes, I think you need to combine the ideas behind a few of my videos. 

 

1. Stretch the image, likely the starless image, to bring out the IFN. Don't over do it. Do it incrementally... it is OK for the galaxies to become nearly white clipped.
2. If the galaxies become too bright too quickly..apply a slow stretch to them by protecting them a little elliptical masks. Sill..let them brighten up though... until it is a little too much.
3. Finally using the same or similar mask apply HDRMT to the galaxies.

The above in some combination will certainly do the trick.

-the Blockhead

Mark Eastman

Thanks Adam, this has been a real challenge but I'm learning a lot.  I am almost done with your process and the trick was to use GHS lightly 2 times on the whole image. Then once with a full strength mask blocking the galaxies....Then the REAL TRICK was to use pixel math to weaken the mask to .9, run GHS again, Then weaken the mask again and run it a final time. I still have to work on the colors and HDRMT and stars but I'm happy with the progress. Thanks so much