Question on processing for mosaic officianados

[daz]

Hi all

I am working on my first mosaic in SGPro and wondered what the recommendations are for processing the panes....

I am capturing calibration frames with each imaging run of course, but when it comes to actually processing the panes, am I better to process each panel fully as a separate image before stitching together - and then I guess there is more work to do to equalise backgrounds, etc. - or should I do basic calibration/aligning/stacking , and then stitch and create one image and process that?

Or is there a batter way entirely?

 

[Uranium235]

Daz, when working on mosaics I always calibrate, stack, crop the edges, run it through registar (if need be), then stitch it together before developing the whole image as one. Maxim is pretty good at putting mosaics together (if you have it). The larger the mosaic, the more difficult it becomes - and the only time I part process before stitching is when there are panes of widely differing background levels. It helps if the black point is roughly the same for each pane.

Processing it all as one helps when you have objects within it that have a large dynamic range (ie: Orion Belt to Sword).

 

Edit: If you have used registar to "map" the panes to an image, more often than not you need to de-rotate the outputted panes by equal amounts (eg: 2deg counter-clockwise), then re-crop to remove the back border that gets inserted by registar.

[Uranium235]

Thinking about it, mosaics would be a good topic for me to cover at the next SGL meet.

[daz]

Thanks Rob - I have PI so hoping the alignment routines in there will do the job.

Ta mate

[ollypenrice]

It is certainly much easier to edge crop, calibrate and DBE (or ABE) the linear files before putting them into your stitching programme. I use Registar but you can do it in PI if you speak PI. I don't speak it well enough for mosaics!! However I save the registered-calibrated individual panels from Registar as well because there may be joints that appear here and there when you stretch the mosaic.

I give the stitched mosaic a test stretch/black point job which I record in Ps as an action. Say there's a visible joint where pane 5 is overlapped by Pane 6. I open the registered-calibrated Pane 5 from Registar and run the action on it so it gets an identical stretch to the mosaic. I slide it into place over the joint and then run a feathered eraser round its edges so that it covers just the visible joint. Flatten.

Now you are ready to give the repaired mosaic the hard treatment.

Note: I think it's far easier to work with RGB than with R and G and B.

Have fun. No image is ever as satisfying as a mosaic. They are very addictive. As I'm typing I'm expecting my fellow addict, Mr O'Donoghue, to walk in. He's on his way, doubtless with plans to go from Polaris to the Southern Cross 'but just in Ha, OIII, LRGB.'

lly