Super Structure (Dim Small )

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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Posts: 370
Joined: Mon Dec 30, 2019 3:49 am

Super Structure (Dim Small )

Post by Startrek »

Whilst working on my latest project , NGC 2070 Tarantula Nebula, I noticed that the Dim Small preset for the Super Structure module does have a negative affect on large nebulous structures like the main body of Tarantula.
Dim small works beautifully on a busy Star field and fine nebulosity in those areas by dimming the smaller stars and smoothing out fine noise / nebulosity but unfortunately it does smooth out detail in main structures as well.
In effect it is “undoing” to a certain degree the work of both Sharpen and SV Decon.
Where Sharpen and SV Decon brought out more structure and fine sharper detail in those huge nebulosity clouds , Dim Small tended to smooth them out or squash them to a small degree. This is only noticeable when zoomed in to say 100% or more but it is a fact.
It’s the first time I’ve noticed this happening.
So to compensate I just reduce to strength from default 100 to around 50 or 60 which did help but then your Star field doesn’t get the full benefit of Dim Small.

By the way I’m using ST V1.8

Has anyone else noticed this minor negative affect and how would one negate this , other than reducing strength

I welcome any advice , comments or tips

This is not criticism on Dim Small or Super Structure as I use this preset and module extensively, it’s just the first time I’ve noticed its affect on pre Sharpened and Deconvolved Structures of nebulosity etc…..

Mike in Rancho
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Location: Alta Loma, CA

Re: Super Structure (Dim Small )

Post by Mike in Rancho »

Hi Martin,

Ya fo sho, Super Structure can have a denoising-type effect, which I think has been remarked upon occasionally.

Makes sense. I think SS is designed to "find" super structures and push other stuff to the background, at least as far as your presets like dimsmall and isolate go. And isolate is even more powerful in this regard.

Lately I've actually been avoiding SS for many images and going straight to DN, using controls like linearity and IFD in OptiDev to set things up such that any "need" for SS towards the end is lessened. I also like stars. :D

I would keep in mind also that the default parameters are just a starting point, and particularly in SS you should then be tailoring all the settings to your target/data. Getting Airy Disk in the right ballpark for your field of view is important, as that will help dictate how energy is redistributed by the module. You can also lessen the power by which SS might fuzz up some detail (especially with isolate) by bumping the gamma back up a bit higher, separate from or in conjunction with strength that you've already experimented with.

Another thing you might try is to skip Sharpen early on (it's kind of cosmetic anyway, as the standard step-down detail enhancing sequence is Contrast-HDR-SVD) and then use it after SS to see if it might bring back those spots you may have lost in SS. Or, do a late subsequent Sharpen but for a different scale, likely medium or small, as set by the first window.

Maybe just the nature of the beast too, as those fine inner details are the not-so-super structures. ;)
Posts: 370
Joined: Mon Dec 30, 2019 3:49 am

Re: Super Structure (Dim Small )

Post by Startrek »

Thanks for your learned reply as always
At least I’m not the only one who has picked this up with Dim Small
To be honest , I found HDR and Life in 1.5 to 1.7 more functional with superior results from that of HDR and SS in 1.8
I don’t normally use the majority's of modules for processing, it’s more of a case by case option
HDR is way too powerful so end up just using Tame in brighter core regions
Sharpen can also provide either good results or detract from fine detail
SS is a great module and use it quite often but again since I picked this little issue up , I’ll be inspecting my results more closely.
Isolate is great for noisy data sets , in particular galaxy images under Bortle 8
Whilst v1.8 is a marked improvement on previous versions , v1.7 was great.
I haven’t upgraded to v1.9 yet , maybe I should ?
Another learning curve with lots of questions to ask I suppose.

Thanks Again
From a Cloudy Down Under ( 4 hours of clear night sky in the past 5 weeks , and we are suppose to be into an El Niño)
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