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PixInsight Arcsinh Stretch

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#76 G. Hatfield

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Posted 26 August 2017 - 03:10 PM

Works like a charm.  I am using the updated version (01.08.05.1353).   I usually use Masked Stretch and compared it with the Arcsinh process.  Looks like the latter preserves more color and background nebulosity.  See attached.  It does tend to leave more of that bothersome pink interior on bright stars, but I think that could be prevented with pretreatment with morphologic transform and a range mask for bright stars.

 

George

Attached Thumbnails

  • comparison archsinh masked stretch sm.jpg

Edited by G. Hatfield, 26 August 2017 - 03:36 PM.

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#77 Chris Talpas

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Posted 26 August 2017 - 11:25 PM

Thank you very much Mark for developing this sure to be useful module.

 

Chris



#78 sharkmelley

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Posted 27 August 2017 - 02:51 AM

It does tend to leave more of that bothersome pink interior on bright stars, but I think that could be prevented with pretreatment with morphologic transform and a range mask for bright stars.

 

 

The pink interior on bright stars is the one of the weaknesses of the Arcsinh stretch.  The ultimate cause of the problem is that these stars are the ones that are saturated in the original exposures.  Because of this, the star interiors have the wrong colour balance once stacked, white balanced and background neutralized.  Because Arcsinh faithfully preserves the RGB colour ratios in each image pixel, it also preserves the wrong colour balance in the star interior.  A pre-treatment or post-treatment that tends to whiten the interiors of those bright stars will help fix this.  Your approach sounds like a good one.

 

Mark



#79 Stamos

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Posted 27 August 2017 - 03:02 AM

Works like a charm.  I am using the updated version (01.08.05.1353).   I usually use Masked Stretch and compared it with the Arcsinh process.  Looks like the latter preserves more color and background nebulosity.  See attached.  It does tend to leave more of that bothersome pink interior on bright stars, but I think that could be prevented with pretreatment with morphologic transform and a range mask for bright stars.

 

George

 

Thanks for posting this.

I've been wondering myself how does it compare to masked stretch which is my favourite tool for stetching.

I will definitely give this a try.



#80 JukkaP

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Posted 27 August 2017 - 04:22 PM

Wonderfull tool, a game changer.

But as you can see in Hatfield post, this is not something you can use solo. Some HT mixed whit Arcsinh is must. You end up whit too supressed image whit only Arcsinh.

I have used this tool only for colour. So I make heavily blurred copy of Arcsinh and aply it only as colour. That way you can get away whit false star colour in your bright stars.

Arcsinh is not one click tool and you must be ready to do much more to your image also.

Edit:
My composition for ArcSinh Strech(see the big letter) was not ok for language check. ;)..

Edited by JukkaP, 27 August 2017 - 04:25 PM.


#81 mikefulb

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Posted 27 August 2017 - 04:29 PM

Wow just tried this for stretching my HDR data for solar eclipse totality and it does wonders for stretching the corona but preserving the inner areas - thanks!


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#82 AgilityGuy

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Posted 27 August 2017 - 08:20 PM

Decided to stay with the previous version of Pixinsight for the meantime to test the functionality of the arcsinh module for Macs.  Could someone please outline how johnpane's Mac version should be installed?  


Edited by AgilityGuy, 27 August 2017 - 11:10 PM.


#83 sharkmelley

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Posted 28 August 2017 - 02:15 AM

Decided to stay with the previous version of Pixinsight for the meantime to test the functionality of the arcsinh module for Macs.  Could someone please outline how johnpane's Mac version should be installed?  

I'm pretty sure you do it the same as for Windows:

  • Unzip the Arcsinh-pxm.dylib file into a chosen folder. 
  • In PixInsight navigate the Menus to:  Process->Modules->Install Modules
  • Use the "Browse..." button on the top right of the "Install Menus" dialog to navigate to your chosen folder and then hit the "Select Folder" button.  The name of your folder will appear as the "Search Directory".  Now hit the "Search" button.  If more than one module appears you may want to to double-click the irrelevant ones, leaving a green tick only against Arcsinh one.
  • Hit the "Install" button.
  • The Arcsinh process will now be available from the Process Explorer window or the Process menu in the usual way.

Mark



#84 johnpane

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Posted 28 August 2017 - 07:18 AM

Here's a rebuild of Arcsinh 1.03 for Pixinsight 1.8.5 on the Mac.

Attached Files


Edited by johnpane, 28 August 2017 - 07:18 AM.

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#85 sharkmelley

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Posted 28 August 2017 - 09:35 AM

Here's a rebuild of Arcsinh 1.03 for Pixinsight 1.8.5 on the Mac.

Excellent!  Thanks!

 

Mark



#86 psandelle

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Posted 28 August 2017 - 10:24 AM

It's a subtle but fun item to use. I'm still playing with out to get the most out of it, but greatly appreciate the work you put in to bring this out. Very cool!

 

Paul



#87 tensor117

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Posted 28 August 2017 - 12:26 PM

Thanks much for this very interesting module.   I have it working fine on Windows, but today's Mac version will not install, giving me the attached segmentation fault.   Presumably, I have something wrong or missing.   Any thoughts?

Attached Thumbnails

  • arcsinhmodule.jpeg


#88 johnpane

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Posted 28 August 2017 - 01:12 PM

Thanks much for this very interesting module.   I have it working fine on Windows, but today's Mac version will not install, giving me the attached segmentation fault.   Presumably, I have something wrong or missing.   Any thoughts?

I'm not sure what's wrong here. I just re-downloaded what I posted earlier today, installed, and tested it and it worked. (I did get a similar segmentation violation error when I tried to load the earlier version). I'm not really equipped to debug/troubleshoot, sorry.



#89 tensor117

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Posted 28 August 2017 - 01:25 PM

John.

 

Thanks for the quick response.  I redownloaded, unzipped, but this time moved the file to the bin directory rather than trying to install from the download directory.  This time it installed with no problem.   So, no issue now.



#90 Magicstar

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Posted 02 September 2017 - 01:17 PM

Hello,

I am trying to install the module and I get this error:

Unsupported API version 155 (expected <=148)

I have the latest 01.08.03 pixinsight.

Thank you!



#91 sharkmelley

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Posted 02 September 2017 - 02:03 PM

Hello,

I am trying to install the module and I get this error:

Unsupported API version 155 (expected <=148)

I have the latest 01.08.03 pixinsight.

Thank you!

You need a later version of PixInsight - either version 1.8.4 or preferably 1.8.5

 

Mark



#92 Magicstar

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Posted 02 September 2017 - 02:12 PM

Thank you!



#93 pfile

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Posted 03 September 2017 - 09:12 PM

macos version works OK for me too, sorry i flaked on building it... the eclipse got to me.

 

rob




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