I've been playing wit PixInsight Deconvolution today but have been unable to get a result I'm completely happy with. This issue is the medium size stars get a white dot in the centre and this gets worse with more iterations. Is there a way to prevent this effect in Decon settings or is there a post-deconvolution fix?
I get a hard edge around saturated cores, which might be what you're talking about, when I don't protect them during decon.
When applying decon I create a luminance mask like you do, although I make the background near black, and try to push the midtones a lot so that I get good decon on my target and less "noise enhancement".
After creating that mask, I then create a star mask (from the original) to capture any of those stars with saturated cores (I usually go with a scale of 5 for this). I then subtract that star mask from the luminance mask I created initially, and then use the resulting mask to protect the image when performing the decon.
I've included:
1. the image pre-decon
2. the PSF used in my decon
3. the deringing mask used in my decon
4. the Lum mask used in my decon
5. the post decon image (50 its)
6. the post decon image with a masked conv of the stars to get rid of the bright pixels
I can't start by reproducing your results because the Pre_Deconv image has a different crop to the masks and the PostDecon image, but... I think the problem you are having is just that you're trying to do a heavy decon on the nebula and this is too heavy on the stars (a perfectly deconvoluted star will become a point source.)
If you want to go that heavy then you'll need to do something like Lee suggested and remove the brighter star cores from the luminance mask. You could subtract a suitably constructed star mask or use PixelMath, e.g. "iif($T>0.6,0,$T)" followed by a slight Convolution blur to take out the star cores.
I just had a similar decon problem. I solved it by using a conventional SNR mask and running a small decon (10 iterations) then I clobbered the stars in the SNR mask [PixelMath: iif(star_mask>0.2,0,$T) followed by a gentle Convolution blur] then hit it with a heavy decon (100 iterations.) That has done the trick and given a gentle star reduction without making them too crispy and still done a strong decon on the nebulosity.
Thanks for the tips Rick. I collected some more data last night so have had another go at this from scratch. Still getting the bright cores in the stars from decon but have applied some convolution with a star mask and this seems to tame it a bit. There is a lot of Ha in this region!
