Jim Misti - m31

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Jim Misti - m31

Postby Rkonrad » Wed Oct 17, 2018 4:30 pm

Here is my interpretation of Jim Misti's data. Comments welcome as how I could improve on it. https://youtu.be/PPoJ-lMwctA

Richard
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Re: Jim Misti - m31

Postby admin » Fri Oct 19, 2018 1:04 am

Great video Richard! Jim Misti's datasets are the gifts that keep on giving. I hope they remain available for years to come.

Some small notes;
The dataset was not Bayered (e.g. it was not acquired through a Bayer filter)
Increasing the Detail Size Range in the HDR module might/should avoid the issue you were experiencing in the core.
When selecting the halo, you could have simply used the Lasso tool. Or you could have used your method and clicked Shrink a few times to deselect the stars, then clicked Grow to increase the halo size again.

Nice!
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Re: Jim Misti - m31

Postby Rkonrad » Sun Oct 21, 2018 2:38 pm

Thanks Ivo!

Point taken - the image was taken with a ccd camera so not bayered. Regarding masking just the halo - I generally prefer not to do this as it seems to be an arbitrary decision as to where the halo actually ends. Also with this part of the image only masked I find that it increases the luminance of the dso disproportionaly though I'll do this when say trying to calm the sky as in the m27 video and other such examples where the snr is poor. This (m31) may not have been the best example but by masking by threshold, it seems more scientific to me. Generally I try to let the mask grab more including stars and some faint nebulocity then I subtract just enough to make the effect more subtle. Hope that makes sense. I'm up for suggestions for sure.

Regarding the "reveal core", I find when I increase the detail size range it broadens the effect ie includes pixels that are not so localized at the core. When decreasing it targets the brighter parts. Am I understanding the function properly?

Thanks Richard
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Re: Jim Misti - m31

Postby admin » Tue Oct 23, 2018 2:40 am

Rkonrad wrote:by masking by threshold, it seems more scientific to me.

That's a really good point and a great consideration to have when processing your image! :thumbsup:
Regarding the "reveal core", I find when I increase the detail size range it broadens the effect ie includes pixels that are not so localized at the core. When decreasing it targets the brighter parts. Am I understanding the function properly?

Yes, that's roughly what happens. The Detail Size Range governs the "context" within which to embed the newly found detail. In terms of the effect, the larger the range, the more "natural" the result looks, but the visibility of newly found finer detail may (or may not) be attenuated in lieu of making everything "fit in to the bigger picture" better.

Hope this helps!
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