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Old 20-07-2016, 09:25 AM
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Andy01 (Andy)
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Experimental Star removal technique

Regarding stars, fwiw I have been experimenting with a new technique for NB imaging to retain "Natural" RGB star colours.
Maybe it's just me but I think magenta stars look very un-natural on NB images.

Instead of completely removing the stars from the Ha/O3 & S2 stacks with Straton or a PS action and potentially degrading the image quality, I've been using several iterations of Annies' Astro Actions "Reduce Star Size" to simply make them a LOT smaller.

Then after the image files are stacked/aligned/hue/saturation etc. I'm using PS>Filter> Noise>remove colour noise to remove the offending star colours. see http://bf-astro.com/hubblep.htm

Then I place my aligned RGB stars as a layer over the top using "Lighter colour" blend mode and viola, happy natural coloured stars and a sharp image.

The remaining tiny stars are basically white and dim so they don't bother me, as long as the main larger ones are a natural colour.

Has anyone else tried something like this?
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Old 20-07-2016, 10:13 AM
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Atmos (Colin)
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It's the basic premise behind what I tried doing last night with my Prawn but I went a little too heavy with the star reduction.
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Old 20-07-2016, 12:24 PM
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Would love to see an example of this posted, maybe with a before/after if you have the time. :-)
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Old 20-07-2016, 12:33 PM
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Likewise please.

Paul
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Old 20-07-2016, 12:43 PM
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RickS (Rick)
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I remove stars from the NB colour and leave them in the NB luminance. That produces an image with mostly white stars. Then, if I feel like adding colour to the stars I blend chrominance data through a star mask, either from a RGB combine or a NB colour mix.

Cheers,
Rick.
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Old 21-07-2016, 10:11 AM
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SimmoW (SIMON)
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Agree Andy, magenta stars suck. Some good ideas there, we all seem to have our own approaches.

If you develop a Cloud Removal technique, let us know!
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Old 21-07-2016, 11:56 AM
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I always find a Vogon constructor fleet gets the job done. :-)
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Old 22-07-2016, 07:44 AM
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I use parts of Geralds video tutorials for enhancing nebulosity in pixinsight. His process basically reduces bright stars down to smaller and its a process you can run a couple of times to remove all the stars, so nebulosity can be brought out then the stars put back later. But following the tutorial I find often the star reduction process gives me sharper rounder more colour looking stars. For you PixInsight I can't recommend Geralds videos enough and for everyone else give them a watch and you might find the same sort of tools in your package of choice. He has some great approaches to universal problems and I never would have thought of using some of the tools in PixInsight for other purposes.
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