What star reduction techniques?

I was looking for Star "reduction", not removal. I rarely like images with no stars. Too many stars can overwhelm the image. That is why I asked about a reduction to suppress them.

Chris

I use the deconvolution method,  and StarShrink in PS,
StarShrink (rc-astro.com)

Cfreerksen:
I was looking for Star "reduction", not removal. I rarely like images with no stars. Too many stars can overwhelm the image. That is why I asked about a reduction to suppress them.

Chris

The process of removing the stars and then adding them back in gives you more control as to what you really get or want so its really part of that “reduction” process that @Lynn K  & @Gianluca Montanari are talking about which btw is better IMHO.

If you don’t want to work with that process then the way I did it before Starnet++  (even after on some things) In Gimp used the Select Color option (with a threshold of about 35) click on a star and Grow to 3-5px/feather 3-5px then go to/Filter/Value Propagate and check “more Black” deselect and use your Opacity slider to control reduction factor.

Lynn K:
I just used Russell Croman's StarXTerminator Photoshop plug-in.  It is designed for CC, but I got it to work with PS5.  Superior to StarNet but not free. $60.

Lynn K.

Thanks for the tip @Lynn K . I’ve always used starnet++for my processing but starxterminator is so much faster and easier. A game changer for me. 👏

Cfreerksen:
I was looking for Star "reduction", not removal. I rarely like images with no stars. Too many stars can overwhelm the image. That is why I asked about a reduction to suppress them.

Chris

For star reduction there are many ways to accomplish the task as previously mentioned.  I feel using Starnet to remove/mask while editing the DSO, then adding them back offers the greatest amount of control.  Once the star mask is added back, EZ star reduction is still an option.  Cuiv just posted a video on his process within Pixinsight further explaining the way.

I know there are a lot of different techniques to reducing star size, but I'm wondering: Is no one using StarMask and then Morphological Transformation in PixInsight to reduce star size anymore?

It works pretty well IMO, I still use it to reduce star size, but maybe I'm not aware about new better techniques ;-)

https://www.star-watcher.ch/image-processing/reduce-star-size-in-pixinsight/

CS
Karol

  The EZ Star Reduction in PixInsight  automates the entire  process and it gives you two choices of methods - the morphological and one based on Adam Block's process that he teaches in his PixInsight courses (except the EZ suite automates it).  I tried both methods in the EZ Star Reduction and like the results based on Adam Block's method better.

On my image that I was testing it on, the morphological achieved approximately the same star reduction but increased the background levels which would require a curves adjustment to compensate for.  The Adam Block option did a good job of reducing the stars, preserved the dark levels and, surprisingly, enhanced some of the fainter nebulosity very slightly but noticeably. 

In my PI installation the EZ Star Reduction script defaulted to 5 iterations, which I did not change.  The tutorial I saw on the script showed a default of 2 iterations but that was from a user with a beta version of script.

YMMV

I sometimes use a combination of MorphologicalTransformation in PI and StarShrink in PS to "dial back" the prominence of a star field.

John

I know there are a lot of different techniques to reducing star size, but I'm wondering: Is no one using StarMask and then Morphological Transformation in PixInsight to reduce star size anymore?

It works pretty well IMO, I still use it to reduce star size, but maybe I'm not aware about new better techniques ;-)

https://www.star-watcher.ch/image-processing/reduce-star-size-in-pixinsight/

CS
Karol

  The EZ Star Reduction in PixInsight  automates the entire  process and it gives you two choices of methods - the morphological and one based on Adam Block's process that he teaches in his PixInsight courses (except the EZ suite automates it).  I tried both methods in the EZ Star Reduction and like the results based on Adam Block's method better.

On my image that I was testing it on, the morphological achieved approximately the same star reduction but increased the background levels which would require a curves adjustment to compensate for.  The Adam Block option did a good job of reducing the stars, preserved the dark levels and, surprisingly, enhanced some of the fainter nebulosity very slightly but noticeably. 

In my PI installation the EZ Star Reduction script defaulted to 5 iterations, which I did not change.  The tutorial I saw on the script showed a default of 2 iterations but that was from a user with a beta version of script.

YMMV

George, thanks for the hint!
I installed the EZ Processing Suite and it's great! It comes with many useful scripts.

CS
Karol

I do not completely remove the stars from my Luminance (Ha), but I do use StarNet to help make the perfect star mask. Original-Starless and then use HistogramTransformation to squeeze the white point way in, and finally a small Convolution. With that mask on the almost-final image I will run MorphologicalTransformation to the point where the stars are still there but small. It is okay if they are too squishy looking because my final step is to run a very light UnsharpMask using that same mask to tighten up the stars. The end result is much smaller, and deemphasized stars.