Author Topic: Help with M57?  (Read 218 times)

Offline nbannister

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Help with M57?
« on: 2018 September 16 10:38:20 »
Hello All,

I've obtained what I think is some good quality data on M57, but I've found it difficult to process to bring out the faint outer shells, and I'd welcome any suggestions people could offer. There's an amazing M57 image taken with the Calar Alto observatory and processed in Pixinsight which is one of the tutorials provided by Vicent Paris, and I found that useful for identifying the main stages of processing, but I didn't find enough information to solve the problems I'm having.

I know there are a number of issues in the image, including some star core/halo problems, but the thing which is really bugging me is the transition from the bright ring, to the outer halo. I generate a mask which, as Vicent notes, is "almost binary", but not quite, so that I can apply deconvolution and HDRM to the core while preserving the outer regions. But I always end up with a really obvious transition between the two regions.

Briefly, my process was:

-Dynamic Crop
-RGB Combine, using 0.4Red + 1.0Halpha for the R channel
-DBE Neutralisation
-Colour Calibration
-Add in Luminance
-Perform Masked Stretch
-Extracted L and used it to generate a mask which protected (almost) all areas apart from the bright ring and regions within. Not binary, I tried to soften the edges to "feather" and help make the transition between core and halo less obvious.
-Deconvolution and HDRM of the ring
-Slight adjustments using Curves to tweak colour of ring
-Remove mask, final adjustments using curves and histogram transformation to get overall colours to my liking.

The colour in the core isn't right, and there's more detail in the data which isn't coming out here. But my big issue, as noted above, is that transition between the inner and outer regions. I read about people who use layers in PS to solve such problems, but I'm sure there must be a way of getting this entirely in PI. Vicent's version of M57 is a spectacular example which doesn't suffer from this problem.

Criticism and suggestions welcome!

Nigel

Link to larger version on Flickr: https://flic.kr/p/29J28ap

Offline Robovet

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Re: Help with M57?
« Reply #1 on: 2018 September 19 03:33:08 »
Possibly you might benefit with some O3 data ?
Dr. Marc Laxineta
Equine Veterinary Medicine
Event Photography
www.robovet.net
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