Issue with Star Reduction

Edward Lubat

Hi Adam

I am having an occasional issue with your star reduction technique, as follows.  No matter how perfectly (I think) I am able to match the substitute pixels to the background, although I get excellent reduction in the size of medium and small stars, the stars that are set against simple background sky end up with prominent halos that cause a very blotchy background that I am unable to deal with.  This seems to be more common in fairly dense star fields.  The substitute pixels seem to end up too bright, but only in the background sky areas, not over the DSO.  Later on in the workflow, I am unable to get the black sky to extend to the star edges without losing the detail in the DSO.  I am attaching an example, with snippets of the image pre star reduction, post star reduction, the substitue pixel image, and a "later on" image after color manipulation.

In less dense star fields, I seem to have more success, for example: 

https://sites.google.com/site/edlubatastrophotos/home/galaxies/ngc-4565-the-needle-galaxy

If you think a one-on-one tutorial might be helpful, I am open to that, although I don't see those listed on your website any more.  Of course, if you think some lessons from this might be applicable to your broader community, I am happy to supply image files.

As an aside, thanks for all of your expert videos, my skills have come a long way: https://sites.google.com/site/edlubatastrophotos/home

Ed

BlockHead

Ed,

I think I see the issue.

You are using the more "advanced" version that uses MMT to create the substitute pixels. 

Part of the issue (I see couple) is that you likely need to apply MMT several times to get the right

background value. But this is correlated with the layers you choose... so it can be tricky.

This method is flexible..but that flexibility comes with some fiddling.

I think you should try the simplified version of this when StarNet is used to generate the subpix.

I think you will find it is easier to get the results you are looking for?

Did you see the video on this?

This updated version is in Horizons I believe.

On another note... incredibly!... a person in the PI community made a script of my method.

I still need to do a tutorial on it... .

This might be good to see as well.

-the Blockhead

Edward Lubat

Yes....I did see the the EZ Star Reduction video, but I have persisted with the "harder" version since you indicated it was more flexible so I was willing to put in the extra work.  But I will try the EZ version, and also play more with layers and # of applications of MMT and see if I can figure it out.

Thank you!

Ed