2019 November: Complete LRGB Tutorial of NGC292, The Small Magellanic Cloud by Christian Sasse, Astronomer in Charge of iTelescope.net
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Veil Nebula Mosaik
Hello Mabula, hello Vincent and happy new year.
I started a long-term project last summer,
a mosaic of the Veil Nebula. It is intended, if it is ever completed, to depict it completely. When I started the post-processing of the 16 panels recorded so far, I realized that this is not going to be easy: calibrating and integrating the panels is true in APP, fast and easy. Also the mosaic creation went without problems, only it didn't look so good. 🤔 Caused by the high background brightness of the summer nights and with some panels it was almost full moon.
No matter which settings I made in LNC (up to 8th degree), the gradients and color gradients did not want to disappear. I also tried it with Pixinsight, there a frame adaptation( LineaFit) of the panels to each other is done during registration.
Gradients and color gradients disappear almost but you can see the seams wonderfully.
So back to APP, then I edited the single panels with remove light pollution and normalized them again. I rebuilt the mosaic and removed the remaining gradients with the tool remove light pollution. Then it looked better.
Then the fine tuning with Starnet++ and then tonmapping and sharpening in Photoshop, finally that came out. 🙂
I don't know if there is a better way, at least it worked for me.
If there was frame adaptation in APP, you could handle difficult images better. But still I have to say that the mosaic is only possible with Astro Pixel Processor (certainly with other software, but the time would have been much higher).
Good that APP exists. 😉
Happy newyear! And a wonderful result I have to say. 🙂
Did you work on the panels first, before making the mosaic? That's what seems to work the best in a lot of situations. I create a panel up to just before the stretch, so including all the ligh pollution correction and color calibration. I save the final, unstretched panel and at the end load those in to create the mosaic. You start out with much better calibrated data then to begin with.
I used the same workflow, but I discarded the color calibration of the individual panels because it was difficult to achieve an even color calibration. I only removed the light pollution, then saved it. Then normalized all panels to the reference frame again to get a grip on the differences in brightness in the background. Saved again and then reload everything to create the mosaic. Then the mosaic is cleared of light pollution again and then the color calibration is carried out. Now the rest of the steps followed.
Hello Vincent, at my current project IC 342.
I have noticed that my dark frames are of poor quality. 😒 Cause true probably, that when creating dark frames the cooling power is too high true. This causes color gradients in the darks, which then affect the lights during calibration.
So new dark frames are created and everything is newly calibrated and integrated.
And already some problems in the lower part of the mosaic have disappeared. 😀