Mosaic problems

[Jan]

I strongly hope my bellow words will not be found inappropriate as they were in another post I made elsewhere on Pixi forum.

I was trying several weeks (!) to make a four field mosaic with Pixinsight tools (Gradient Merge Mosaic processing). Unfortunatelly under ANY settings I did not get ANY usable results - I was always getting artifacts around bright stars in transition areas. The fiddling with the  settings just resulted in different level of the artifacts. I have seen the similar problem being discussed around, but I did not see any advice for real solution. I have seen an advice to remove the bright star from one of the two merged fields with clone tools.. I did not use this method as i find it totally against the philosophy of Pixinsight, which I like for clean mathematical solutions, no "painting" the image.

Here is the screenshot. The left image completelly processed with Pixinsight (unfinished...), the right image - channel combination in pixinsight, then I used another software (freeware) to stitch the TIFF files, and then reopenning Pixinsight and completing the processing.

[Zocky]

The best way for getting the solution for your problem, would be to upload those 4 files on Dropbox or some other filesharig site. I am sure you will get back all the answers for your questions.

[georg.viehoever]

Hi Jan,
Unfortunately, removing bright stars from one of the contributing images is the only solution that seems to work reliably. I dont think this is "painting" since you still use real data from one of the images. This is quite different from some of the procedures used elsewhere that "invent" data in places where no data exists, such as in saturated parts of the image.
You are free to use any tool you like to complement PI. If ICE works for you: use it.
Georg

[TobiasLindemann]

Hi Jan,
the last days I had the same problem. I the documentation it says: 
Stars cause problems at seams

Try increasing the feather radius parameter. If this still fails, try use with stretched images. If everything fails, use the manual clone stamp tool to remove the offending star from all but one of the contributing images.
What helped for me is to do a HistogramTransformation before the StarAlignment(for Mosaic). Don't activate the frame adaptation in StarAlignment when you use the GradientMergeMosaic and leave the Feather between 10 and 15.

Greetings
Tobias
 

[TobiasLindemann]

I have another question: how do you align more than two mosaic-images with StarAlignment?

[georg.viehoever]

Like this maybe: https://www.youtube.com/watch?v=H2r3ZYqCaP8
Georg

[TobiasLindemann]

Hi Georg,
ok, I see 
I haven't realized that this module is from you. Congratulations, it works great :-)

Greetings
Tobias

[georg.viehoever]

I haven't realized that this module is from you. Congratulations, it works great :-)