7 replies to this topic

[BeltofOrion]

On May 24th I uploaded a photo of the Bubble Nebula that I had obtained by processing Seestar 50 data with Siril 1.4.0 ... Beta 2. This photo is from the very same data but processed with PixInsight ... and a very quick processing at that.  In my opinion, this  is a much better image than the first ... especially as far as the stars are concerned. One thing's for certain, though... either image shows that the little Seestar 50 is capable of producing a very decent image.

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[BrickInTheSky]

Why most stars have a black halo around them? Is that your artistic take and deliberate?

[Peter Besenbruch]

Why most stars have a black halo around them? Is that your artistic take and deliberate?

I can think of two reasons. Pushing unsharp masking (and probably other forms of sharpening as well) too far will do this. Another possibility is doing a star removal, processing the nebula and stars separately, then recombining. If when processing the stars you tighten them up, they will be smaller than they were in the original. There may be other reasons.

[BeltofOrion]

Why most stars have a black halo around them? Is that your artistic take and deliberate?

Not artistic… and definitely not deliberate. As a last step in PixInsight … since the stars were blocky … I decided to use the Resampling process. Stars were perfectly fine after that step. But I took that result into Photoshop since I wanted to try out the Nik collection software plugin … specifically Viveza 2 … and also the Topaz sharpener plugin. The dark halos came about as a result of letting Topaz AI do its thing. As I said, it was a rather quick processing of the data. I mainly wanted to see if I could get a better image than the one I got with Siril. I’m sure I could improve on it further with a little more time spent …but more spare time is something I really don’t have right now.

[BeltofOrion]

I can think of two reasons. Pushing unsharp masking (and probably other forms of sharpening as well) too far will do this. Another possibility is doing a star removal, processing the nebula and stars separately, then recombining. If when processing the stars you tighten them up, they will be smaller than they were in the original. There may be other reasons.

Right! Came about as a result of using Topaz AI’s suggestion for sharpening. The stars were perfectly fine after using the last step of PixInsight … Resampling.

[Peter Besenbruch]

… and also the Topaz sharpener plugin. The dark halos came about as a result of letting Topaz AI do its thing.

So pushing the sharpening a bit too hard. The bane of every astrophotographer... 

Edited by Peter Besenbruch, 05 June 2025 - 04:12 PM.

[BrickInTheSky]

Very true. I usually TRY with the lowest setting and probably in 90% undo the sharpening: it hurts more, as far as my taste goes, than helps. I like dreamy soft images…

[WillR]

I like it, nice detail and composition. I see what BrickInTheSky is saying about the black halos though. This is in the Milky Way and there are a lot of stars to deal with. Maybe you could stretch the fainter stars (the brighter stars don’t seem to have this problem) a bit more. I have no sides if that would solve it.

 

The only other thing I’ll say is it would be nice to see a little more color variation to make the Bubble stand out from the surrounding nebulosity.  I know there are scripts in both Pixinsight and Siril that can do this. (But I haven’t tried them)