Best way to Mosaic

[rogerg]

OK, so normally Photoshop, PTGui and the like get me by for dealing with mosaics. But I find complex deep space mosaic very challenging. Case in point attached, LMC.

Any suggestions on dealing with it in a way that won't leave spending my remaining years at the computer attempting to finish the mosaic?

... because I've already spent way too much time!

Thanks,
Roger.

[Atmos]

Having been where you are quite recently I have personally found that the best way is to do the same processing on each frame, doing quite minimal processing premosaicing. I basically set black point, noise reduction and stretch.

After every frame has been "processed" individually, don't worry if the individual ones don't looo crash hot as more processing can be done after they've been stitched together. I have been using Autopano Giga, not cheep but has worked well for me. After it has stitched them together it doesn't look great but after some curves and levels playing it works well.

The first image is a 2x3 panel of the LMC. The second is an 8x10 panel of the galactic centre.

[doppler]

As long as you have a good overlap between images canon photostitch http://en.lo4d.com/windows/camera-software is a quick and easy way to do mosaics, or you could try AutoStitch http://matthewalunbrown.com/autostitch/autostitch.html. both are free to use.

[rogerg]

I find that the colours vary between mosaic sections. In my case each mosaic section is taken on different nights because it's a relatively big project ... so setting black point isn't enough .... Ihaven't worked out a way to accurately colour match each frame to each other frame in the mosaic. Hmm.

[Atmos]

My process in PixInsight is as follows.
1) Stitch 2-6 frames together that have both bright and dark areas; this is my template.
2) Set black point, save instance.
3) Histogram stretch, save instance.
4) Revert the template mosaic back to before the black point set.)
5 Use the instances to process each image. This means that every image has the same black point relative to a template. Every image has the sae histogram stretch as well.

I have not yet done a multinight mosaic so I cannot say whether it's work
But I get the same issues as you're currently getting doing them individually as well.

[multiweb]

I've always used Photoshop to blend in the seams between panels. I register the panels with Registar. For the colour differences between panels I do the colour balance in CCD Stack with pixel maths on the FITS prior to save them to 16bit TIFF then do the stitching. You have to treat every panel as a stand alone process. The end file is usually too big to handle in RAM and do any major changes.

[sil]

Microsoft's ICE (Image Composite Editor) does a great job at mosaics, free too and gumby proof. For perfectionist control: Hugin, also free.

[rogerg]

I'm intrigued by your process with PI as I'm sure PI would provide my best chance at conquering this ...



So, the first thing you do is stitch up to 6 of your frames together (presumably each being a stacked result of several exposures but with minimal post-processing performed) .... but if you do this how do you adjust the levels or such of each to make them balance? What process are you using to stitch them together?

Thanks,
Roger

[Atmos]

When I do my initial stitch I do no processing at all, just stitch the raw stacked frames. The idea is to create a processing template from a group of frames and then doing the same processing on the individual frames later. This is why I save each step along the way (create the instance).

I'll take a photo of my processing screen tomorrow if you'd like.

After I have processed each individual frame I load it all into Autopano Giga but you could use any number of stitching programs I imagine.