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How do I use the Star Halo Reduction script?

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#1 PhotonHunter1

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Posted 21 September 2019 - 08:42 PM

I am attempting to use the StarHaloReducer script in PI, and without documentation I am struggling to figure out how to successfully use this tool. Any advice or instructions on how to use would be most appreciated. Thanks.

 



#2 jerahian

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Posted 21 September 2019 - 09:19 PM

It definitely takes a little getting used to:

 

First off, your image must be non-linear for it to work:

1) Draw a Preview immediately around the halo you are trying to reduce

2) With the Preview tab active, launch the SHR.  You should see your star and halo in the top section of the script window.

3) Crank up the "RGB/K" parameter value to something like .75 or more.  This will allow you to see the halo reduction mask clearly.

4) Make sure the mask is perfectly centered around your star.  To do so, you can nudge it with the "Star halo center" X and Y values.

5) Now alter the "Halo reduction radius" and "Star halo radius" until the mask covers the halo you wish to reduce adequately.

6) Bring the "RGB/K" parameter back down towards 0.5 slowly.  At some value higher than 0.5, the reduction mask will blend well with the background.  Blurring your eyes helps here.

 

In some cases, this process will leave a mild dark ring around the perimeter if the halo isn't sharp in its outline.  At this point, experimentation is the only thing left to get you the reduction you seek.

 

GL&CS,

Ara


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#3 PhotonHunter1

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Posted 22 September 2019 - 08:14 PM

Ara, big thanks for the detailed instructions - It would have taken me a lot longer, if ever, to figure out how to use this script.



#4 PhotonHunter1

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Posted 23 September 2019 - 12:19 AM

Ara, I've followed the steps you've laid out and am good up to #5 where I've made a few assumptions, perhaps incorrectly so, on how to use the script at this point. I've listed my processing steps below:

  • Follow your steps 1-4.
  • I then move the halo reduction radius slider all the way to the right.
  • I then move the star halo radius slider to the right until the black circle matches the circumference of the halo.
  • Follow your step 6.
  • I click OK.
  • I save the fullview image that the script creates renaming it SHR1.
  • Rinse repeat the above steps for the remaining haloed stars in my image.

I appreciate any additional guidance or correction to my assumptions and/or processing. Thanks!


Edited by PhotonHunter1, 23 September 2019 - 01:40 AM.


#5 jerahian

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Posted 23 September 2019 - 11:44 AM

Ara, I've followed the steps you've laid out and am good up to #5 where I've made a few assumptions, perhaps incorrectly so, on how to use the script at this point. I've listed my processing steps below:

  • Follow your steps 1-4.
  • I then move the halo reduction radius slider all the way to the right.
  • I then move the star halo radius slider to the right until the black circle matches the circumference of the halo.
  • Follow your step 6.
  • I click OK.
  • I save the fullview image that the script creates renaming it SHR1.
  • Rinse repeat the above steps for the remaining haloed stars in my image.

I appreciate any additional guidance or correction to my assumptions and/or processing. Thanks!

I think you have it.  Honestly, I don't have a full appreciation of the difference between the "Halo reduction radius" and the "Star halo radius."  Both seem to control/limit what seems to be the same halo mask, so that part I'm still a little unsure of.  Initially, I thought one controlled the inner circle of a donut while the other controlled the outer circle, but I can't seem to make them behave that way.

 

Two other things:  I definitely leave "Soft border mask edges" enabled, as that seems to blend the dark outer ring that may form with the background.  Also, sometimes I drop the "Star protection radius" down from the default 12 to a lower value, even zero.  It definitely takes some experimentation.

 

Regardless of some of its quirks, it's still a powerful script that effectively removes halos for the most part, and much more cost effectively than high-end filters flowerred.gif

 

-Ara


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#6 PhotonHunter1

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Posted 23 September 2019 - 10:48 PM

SHR over a new filter set - for sure. I’ll keep playing with the settings and see what I can learn. Thanks for the additional info. 




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