UPDATE FROM MABULA
I have had a very rough 2 months unfortunately health wise. I was struck 3x in a row with bacterial infections. The second infection occurred  after a routine hospital checkup and I became very sick. I had to rest and take a lot of antibiotics. Once I was recovering and restarting work 1 month ago, I again became sick. The infection was not yet gone, so even more antibiotics and rest was needed. Needless to say, it took a lot of my energy and I needed a lot of rest.
Finally, the infection is really gone and my energy is coming back step-by-step now and I have started work again. I am terribly sorry to have kept you waiting for support. I will address all outstanding questions and e-mails step-by step and will be on the forum daily from today.
APP 2.0.0-beta47 will come soon as well, a lot of work was already completed before I became very ill, so the release is also nearly ready for you. Beta47 will be much faster actually. Many workflows will be more than 2x faster, mosaics can even be 10x faster than before because registration really received a major boost... all compared to beta46. Â Before I release it, I will make sure that everything is working properly and then I will release it.
I'm currently working on a mosaic of the Carina nebula. Four panels - mono camera - four filters (HaRGB).
This means I will have 16 integrations to combine. It seems to me there are two ways to go:
   Option 1 - Mosaic the panels for each filter. Then do RGB combine, light pollution reduction, etc on the "mosaiced" images.
   Option 2 - Start with RGB combine, LPR, etc for each panel and combine the mosaic as the last step in APP.
I think each option has some advantages. I have been using Option 1 for testing while I am still getting data and it seems to work OK.
My question is - can a strong case be made for one of these options over the other ? Or does it just come down to minor differences/personal preference ?
I don't know enough about the interaction between normalisation and mosaic processing, but I would not be surprised if Option 2 was technically superior. I would apreciate any comments.
thanks
JC
Option 2 is better I think (there are more ways to Rome for sure), but I would also try option 3. Which is creating the panels first, so panel 1 fully integrated as HaRGB. This panel doesn't have to be corrected yet as creating a mosaic will change things anyway. Load these panels as lights and then create the mosaic. This mosaic can then be fully corrected.
ps. I guess your option 2 is basically this, I just removed the correction steps. 🙂
Vincent
Thanks for your comment. I hadn't even considered your option 3, but I suspect you may be on the right track.
I was hoping for a technically based/justified response - maybe even some words of wisdom from the man himself, although I wouldn't want to distract him from getting 2.0.0 stable ready for release (grin).
regards
JC
The man himself is very busy, but I can ask if you really need that. 🙂 One of the things to use my option is that, while you can correct the panels first as well, the calculation of creating the mosaic changes the background again. This has to do with the overall statistics in that algorithm. Which makes that it's better to correct after creating the mosaic.
Besides that combining entire mosaics and registering those with each other is an ok option as well, but less manageable when the mosaic gets bigger. The algorithm is optimized for creating the mosaic from the panels.
Thanks Vincent
I think you have given me enough to think about and move forward - probably don't need to bother the man.
regards
JC
No worries if you do need more detailed information. If anything is unclear in your further testing, just give us a shout.
Vincent
Here is my finished mosaic, probably with too much colour saturation as I can't help myself.
I tried processing this the way you suggested in option 3, but it didn't work well. I ended up with something with different colour issues in different parts of the image. Perhaps I stuffed something up, but anyway it was worth a try.
I ended up going back to option 1. I started by first creating a mosaic for each filter, then LPR for each filter and then processed more or less normally from that point onward. The star colour calibration step didn't work as normal - I suspect the starfield was so dense that APP mistook stars for nebulosity, but I'm just guessing about that. One thing that supports that guess is that I tried a star reduction and it only changed a tiny fraction of the stars in the image. I ended up doing star reduction outside of APP.
Still, I'm fairly happy with the end result.
Carina Nebula (downsampled) 2x2 mosaic.
The different colors in the end result can be normal, due to variations in calibration between the panels. But that usually is solved with some careful light pollution correction. In any case, you found another workflow that seems to have worked nicely. If you want I can always have a go as well. 😉
Thanks Vincent - I think I'm good for now. I did try to fix the local colour issues with LPR, but it was pretty difficult with the way the nebula sat in each panel.
Anyway - thanks for your help.
JC
