Ngc 6744

[Startrek (Martin)]

Alex,
Workflow for creation of good Star Mask and using Shrink , Dim Small and Isolate ( Superstructure) to reduce Star field in Startools v1.7 or v1.8

Star Mask

NB: As stars are made up of many pixels , undersampled data , heavy binning or heavy cropping will reduce resolution and therefore reduce the number of pixels that make up a Star. This will have a knock on and negative affect in creating a good Star Mask as Stars will end up blocky when you zoom in making it impossible to ensure a good round Star Mask covering the whole stellar profile of the Star.
If your image scale is oversampled ( below 1 arc sec per pixel ) which is ideal then recommend Cropping edges only and maximum Bin 50%

Press Mask at top
Then press Auto
Set Filter Sensitivity to 1
All other settings default
Press Do
Basic Star Mask appears

Note 1: Any stars not sampled or green can be masked by setting Brush Mode below to “Flood Fill Lighter Pixels “ and then click on Star core white pixels to start mask and click on white pixels just outside green mask to expand mask.
Alternatively you can use Brush Mode “Lasso” and draw mask around Star
Note 2 : Any small or tiny stars not fully masked , just use the “Grow” button at the top. One click at a time. If you grow too big use the reverse button “Shrink”

Important !!!
Ensure the whole Star is masked out green , slightly overlapped the better



Shrink Module

To be used after main processing just before Colour module and final noise reduction

Make sure you have a good Star Mask set with all stars sampled or green

Select Shrink
Shrink may ask you to set a Star Mask , select “Keep Mask as is “
Ensure Mode setting is set to “Tighten”
Adjust iterations from default 10 up to 20 and use before and after button to inspect Star size and brightness reduction
All other settings leave as default

NB: If Stars have large than normal halos use Uni glow Strength and Uni glow Kernel sliders below to reduce halos
Once satisfied with Star field press Keep




Superstructure Module ( Dim Small and Isolate presets )

Can be used after Shrink and either before colour or after colour module and before noise reduction

Make sure you have a good Star Mask set with all stars sampled or green. Then press “Invert” at top so that stars now are “not sampled” white and background is green or sampled
Press Keep

Now select Superstructure Module
Superstructure may ask you to set a Mask, select “Keep Mask as is”
Then press “Dim Small” preset at top.
The only slider to adjust will be “Strength” Default is 100%
NB: Don’t increase past 100% only reduce down to 90, 80 , 70 , 60 to 50%
Once satisfied with the Star field reduction press Keep

Further Star reduction ( Optional ) is “Isolate”
Select Superstructure module again
Keep Star Mask as is
Select “Isolate” preset at top
Reduce “Strength” from default 100% down to at least 50% or 40% as this feature is quite aggressive
Once satisfied with Star field reduction, press Keep

Now select Star Mask at top again and press “Clear” then “Keep”

Star reduction is now completed !!

Your now ready to finalise your processing using Colour and then final Noise Reduction


Hope the above helps

Cheers
Martin

[xelasnave]

Thanks Martin
With the new computer StarTools was only loaded three days ago so it would be the latest...I am not sure with the lap top but ( cant look at it right now) but it would be within the last 12 months.
Alex

[xelasnave]

Martin Thank you very much for the work flow as I just relied on the "create a mask" tool and thinking about it taking more time should be worth it.

Because I crop heavily I don't bin..I dont know if that is advisable?


I am putting in another tri pier system today so finally all three scopes will be on solid bases.
Things are finally coming together..two Asiair plus have been shipped, new wheels are here and I think I have licked the dual winch drum issue..the Arduino however was just a box of parts with no instructions so I will order another and some relays...

Thanks again...can you do anything about the weather please

Alex

[Startrek (Martin)]

Alex,
Always glad to help ( where possible)
Wet in Sydney too
Maybe an Aztec Sun dance might help ?
In regard to your image size and a Star Mask my native size off DSS when loaded into Startools is around say 6500 x 4500 pixels and after I crop edges for stacking artefacts and either a 50% to 60% Bin ( don’t forget you can use the slider to adjust Binning and not just rely on the presets up top ) that gets me down to around say 4800 x 2800 pixels which is excellent for a good Star Mask
Just remember it’s all about sampling with the number of pixels
I’m oversampled with my newts and 2600MC ( 0.86 to 0.42 arc sec per pixel ) so I have ample pixels to cull my image size down without my Stars looking really “blocky” when you zoom in a bit
Using your RASA 11 and ZWO 2600 cameras your image scale or sampling will be 3.76uM x 206.3 / 620mm focal length = 1.25 arc sec per pixel . So your bordering on being undersampled which makes it difficult. It all depends on your final image size
A quick check is to zoom in to 100% and if your Stars look roundish not blocky then the image size is good and a Star mask will work well for Shrink and other modules
I can zoom in to 200% or even 300% and my Stars still look roundish

Setting up my image size and resolution is the first thing I check and of course noise floor as well , before I jump into real processing with AutoDev, HDR , Sharpen and so on ….

I was going to talk about the new Deconvolution ( SV Decon ) in version 1.8 but I’m still having a few issues with it . It needs well oversampled data and quality data to work well. I’ve been posting stuff on the Startools forum and Ivo has been most helpful ….., but that’s for another day

Cheers
Martin

[xelasnave]

Very heavy rain here such that we stopped work but have three holes and all star pickets in ...
I have tried to join StarTools forum..they acknowledged my application and said I would receive an email when approved but it never came..I guess they know me there

Thanks again Martin.

Alex