Mosaics and Filters/RGB combine

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