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Solar Eclipse Image Sequence Processing

Posted: Sun Nov 05, 2023 4:19 pm
by JohnnyC
I'm hoping that some of the smart folks here can offer some advice. I took hundreds of Ha images of the 10/14/23 annular eclipse, but I keep bumping up against the same walls in terms of processing. Has anyone here found a way to align the images of the sun in this type of sequence? ImPPG has an Image Alignment feature, but it can't handle a solar eclipse sequence. Also, does anyone here know of an effective way of matching the brightness of the eclipsing solar disc from one image to the next? Maybe something analogous to PI's LinearFit?

Thanks in advance,

Re: Solar Eclipse Image Sequence Processing

Posted: Sat Nov 11, 2023 11:23 am
by rigel123
I haven’t tried with an eclipse sequence but have you tried Photoshop by bringing in files as layers under Scripts and checking the attempt to align frames box? I find with images that have disk features on them that PS does a better job of alignment than ImPPG.

As to balancing the brightness of the disk I was going to suggest PI's linear fit!

Re: Solar Eclipse Image Sequence Processing

Posted: Wed Nov 15, 2023 2:15 am
by EdAstle
I wrote some software back in 2006 to align around 30 total eclipse pics, because I couldn't find anything "off the shelf".
That took about 6 months of inventing - centroids, edge detection, auto generating Photoshop javascripty stuff.

15 years of tweaks later and I'm ready to print.

The centroid of an annular eclipse will shift so it'll be hard for any software that doesn't also do edge detection.
ED is hard when you get to fluffy solar "edges" 3000x2000 pixels or suchlike. The matrices become large and slow.

So my algo reduced my 3000x2000 images to 300x200 to make it faster first time round.
I had a dual core Pentium back then - oh yeah. A doubled stacked CPU.

To cut a long story short - nothing beats the human eye for KISS principles.

Bring image #1 into Photoshop or suchlike.
Bring image #2 into Photoshop or suchlike. Set the layer merge to "difference"
Use keyboard to move one image relative to the other.
When the two are aligned the difference will be nigh on blackness.
Rinse and repeat for the other 99 images.

I promise you that's quicker than faffing about with software for 15 years :D

As for making all frames of an eclipse "equalized", I would say it is that loss of equilibrium which makes an eclipse so profoundly unsettling (to the neophyte). In Turkey 2006 I went from hot and happy to shivering and not able to use my camera properly because I had no idea "when you turn the sun off" it gets so cold so quickly.

It's a fine balance - the art or the science. Humans are great at both.
Although me personally - neither :)