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Dear Alnitak, I hate you

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#1 shawnhar

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Posted 06 January 2015 - 08:58 AM

2 hours 40 minutes of 10 minute subs with 12nm HA filter last night

 

Flame2hr-40_small.jpg


Edited by shawnhar, 06 January 2015 - 09:23 AM.

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#2 proteus5

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Posted 06 January 2015 - 09:06 AM

But it's nice and round :grin:.  NIce image!



#3 shawnhar

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Posted 06 January 2015 - 09:40 AM

Thanks Robert, if it weren't for that dam star I would try for a mosaic of this area

 

Mosaic.jpg


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#4 Footbag

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Posted 06 January 2015 - 09:43 AM

It's a beast.  I figure it's going to be the first real test for my WOStar71.



#5 Madratter

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Posted 06 January 2015 - 09:53 AM

I have had trouble with it in the past as well. :( I now use it and the Pleiades as tests of my optical train.



#6 David Ault

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Posted 06 January 2015 - 10:08 AM

Hey Shawn,

 

I was able to mostly remove the halos using PixelMath in PixInsight.  I essentially measured the location of the rings and their brightness relative to the background and then made a model of them that could be subtracted.  I first made an entirely black image of the same size as the original then ran these PixelMath steps to create the model:
ShawnharPM01.jpg

 

ShawnharPM02.jpg

 

Here's the result (this is stretched so you can see it):

ShawnharCircles2.jpg

 

I then blurred it to soften the edges (also stretched):

ShawnharCirclesBlurred2.jpg

 

Then I subtracted the model from the main image:

ShawnharPM03.jpg

 

This left some edges that needed to be cleaned up with clone stamp, but this could be improved by better modeling the halos.  As it was it only took a couple minute of clone stamp work to cleanup what was left.  Here's the result:
ShawnharCirlcesRemoved2.jpg

 

Regards,

David


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#7 Madratter

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Posted 06 January 2015 - 10:14 AM

I never would have thought to do that. Nice job David!



#8 anismo

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Posted 06 January 2015 - 10:23 AM

Excellent stuff David! Looks like shawn can be  back in the business of building hires mosaics! That is some nice data there



#9 shawnhar

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Posted 06 January 2015 - 10:25 AM

OMG David, that is INCREDIBLE!

 I have to try and reproduce that in photoshop



#10 terry59

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Posted 06 January 2015 - 10:31 AM

Good use of PixelMath :)



#11 Goofi

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Posted 06 January 2015 - 10:42 AM

David .... wow!   :waytogo:  :waytogo:



#12 woodscavenger

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Posted 06 January 2015 - 10:51 AM

Should call that program Pixel wizard.  nicely done.  Great save



#13 everstar

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Posted 06 January 2015 - 11:14 AM

I vote that we blast Alnitak away with the Death Star first chance we get, that will pretty up all our images!  :)



#14 shawnhar

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Posted 06 January 2015 - 01:09 PM

I can't get photoshop to reproduce David's result, that is just amazing.

 

stitchTry1.jpg



#15 Goofi

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Posted 06 January 2015 - 01:35 PM

Shawn, Photoshop doesn't have pixel math ... I'm constantly amazed at what you can do with it.

I know some people who seem to do all their processing using just pixel math.

 

Logic was never my strong suit, and writing those equations just short circuits my mind.

I understand what David did, but I'd never have thought of it on my own.

Fortunately, I can cut, paste and steal to make my own images look a little better.   :)

 

Dynamic Background Extraction, Pixel Math, and the ability to work with linear data while seeing what's going on using a Screen Transfer Function all justify the cost of the program.  I wish I'd started using it back when I was using the DSLR 


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#16 Jon Rista

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Posted 06 January 2015 - 01:59 PM

Hey Shawn,
 
I was able to mostly remove the halos using PixelMath in PixInsight.  I essentially measured the location of the rings and their brightness relative to the background and then made a model of them that could be subtracted.  I first made an entirely black image of the same size as the original then ran these PixelMath steps to create the model:

...

This left some edges that needed to be cleaned up with clone stamp, but this could be improved by better modeling the halos.  As it was it only took a couple minute of clone stamp work to cleanup what was left.  Here's the result:
ShawnharCirlcesRemoved2.jpg
 
Regards,
David



That is some awesome work, David! Way to use PixelMath! :D

#17 hytham

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Posted 06 January 2015 - 03:02 PM

David,

Will you please post the link to the tutorial? I had it bookmarked and forgot to save it during my last rebuild.

Thanks!

#18 David Ault

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Posted 06 January 2015 - 03:10 PM

Thanks guys!

 

It really is amazing what you can do with PixelMath. :)

 

Shawn, I'm sure it can be done in Photoshop.  Hopefully someone with Photoshop knowledge will chime in.

 

Regards,

David



#19 David Ault

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Posted 06 January 2015 - 03:24 PM

David,

Will you please post the link to the tutorial? I had it bookmarked and forgot to save it during my last rebuild.

Thanks!

Hytham, I was unaware there was a tutorial on how to do star halo removal with PixInsight.  I just did it this way because it made sense to me.  There is a halo removal script but it's somewhat limited and wasn't working for this monster.

 

Regards,

David



#20 Jon Rista

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Posted 06 January 2015 - 04:22 PM

How did you determine the formula to recreate the halo? Maybe you could write up a tutorial yourself and share it on a blog somewhere. This is an extremely useful technique.
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#21 PeteM

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Posted 06 January 2015 - 04:28 PM

Great use of Pixel Math David. I would love to see any kind of tutorial about what you did in more detail. PI sure is a killer program and very well worth its cost. Besides a good mount, PI is the next most important purchase someone needs to make.


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#22 David Ault

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Posted 06 January 2015 - 04:53 PM

I can certainly put a tutorial together.  I've got some day job stuff to deal with but hopefully I can get to it in short order.

 

Regards,

David



#23 hytham

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Posted 06 January 2015 - 05:03 PM

Hytham, I was unaware there was a tutorial on how to do star halo removal with PixInsight.  I just did it this way because it made sense to me.  There is a halo removal script but it's somewhat limited and wasn't working for this monster.

 

 

 

Regards,

David

 

 

 

Well, darn.

 

I had seen a tutorial written up by one of the PI guys using a similar technique with a boat load of info and was hoping you had referenced it. I was trying to write out the equation, but kept using the wrong syntax for the background measurements. Now I can see my syntax error referencing yours. Thanks for that!

 

The halo removal script has worked for me in the past with some success, but i found it  inconsistent which admittedly could be my ignorance of its potential.


Edited by hytham, 06 January 2015 - 05:08 PM.


#24 jbalsam

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Posted 07 January 2015 - 09:38 AM

Processing those halos out is an impressive feat. My recommendation would be to get rid of them at the source, though.

 

Some rough calculations (involving some gueses about which scope you were using... I assume it was your 6" Schmidt Newt) indicate that the source of the reflections is likely to be your filter. I calculated that the surface was roughly ~30mm from your sensor, which would be your filter (unless you have some other glass surface that is in that ballpark).

 

Use this online calculator and input the actual stats from your setup: http://www.wilmslowa...lae.htm#REFLECT

 

I grabbed the image from your post and measured the diameter of the halos to be roughly 720 pixels. You may want to measure it in the original file, don't take my word for it.

 

Run the numbers, and if the indication is that the culprit is your filter, you can remove the halos by buying a filter with better anti-reflection coatings. Good luck!


Edited by jbalsam, 07 January 2015 - 09:46 AM.

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#25 jerry10137

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Posted 07 January 2015 - 04:42 PM

Now that's how you use PixInsight!

 

Awesome job on the halo removal!




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