Problem with GradientMergeMosaic

[footbag]

David Ault did a great presentation on "What to do when GMM doesn't work properly" 

The big takeaway for me was his DNALinearfit script.  It really worked well at fixing every issue I had with my mosaics.  From pinching black star issues, to darkened overlapped panels.  I spent days on this data, then used his script and it worked 1st time out. 

His site - http://trappedphotons.com/blog/?p=994
His Script - http://trappedphotons.com/files/tmp/dnaLinearFit.js
His Presentation - https://youtu.be/p6UaFbh5_SI

[dnault42]

Thanks for posting this Adam.  I've been meening to add to this thread but just keep running out of time.

I just want to clarify, there are some reasons why I haven't promoted this script more or posted it here the PI forums.  While it is deterministic it is not as stable as the LinearFit process.  If the mean is smaller than the median of the image it can result in, well, garbage.  Still, like Adam said, I have found it very useful for mosaics, since it only uses the overlapping area for determining the fit and keeps black pixels as black so that GMM is not affected.  I also have it report the number of pixels clipped (low and high are separated) so you can check if something is going wrong and make adjustments (like use a different image as reference).

If you are having issues like this it's not going to hurt to try the script between the panels and see if it helps.

Regards,
David

[llpastro]

I am having problems getting PI to recognize the script.  Would someone be so kind as to refresh my memory on how to install it?  Thanks in advance.

Larry

[dnault42]

Hi Larry,

Copy the script to your PixInsight\src\scripts directory (for Windows that's usually something like C:\Program Files\PixInsight\src\scripts).  Then in PixInsight go to the SCRIPT->Feature Scripts... menu option.  On the form that pops up, click the Add button and select the same scripts directory.  It will search for any new scripts in that path and add them to the active scripts.  The 'dnaLinearFit 0.1' script should now show up under SCRIPT->Utilities or in the Process Explorer under <Scripts>, <Utilities>.

Regards,
David

[llpastro]

Thanks, David.

Larry

[Warhen]

Yes David and Adam! Bravo again David, dnaLF gave GMM what it needed to adapt 4 panels of M45 to each other where Frame Adaptation and GMM could not succeed perfectly w/o it! There are a lot of bright stars and reflections in that field, but the script coupled with the other two excellent tools did the trick. It's being added to the Inside PixInsight book!

David Ault did a great presentation on "What to do when GMM doesn't work properly" 

The big takeaway for me was his DNALinearfit script.  It really worked well at fixing every issue I had with my mosaics.  From pinching black star issues, to darkened overlapped panels.  I spent days on this data, then used his script and it worked 1st time out. 

His site - http://trappedphotons.com/blog/?p=994
His Script - http://trappedphotons.com/files/tmp/dnaLinearFit.js
His Presentation - https://youtu.be/p6UaFbh5_SI

[dnault42]

Thanks Warren!  I need to find some way to make the link permanent yet still be able to update the code.  I'll have to look into that.

Regards,
David

[dnault42]

I've updated my dnaLinearFit script to deal with color channels.  You can download it from here.

It will now also support mismatched numbers of channels between frames.  So you can linear fit all channels in a color image to a reference image, for example an RGB image to a luminance or Ha frame.  If you have two color images it will linear fit red to red, etc.

Warren,  I should be able to keep this link stable going forward, so if I make updates the link shouldn't change.

Regards,
David