Full Io Orbit How-To, Part 3 -- Post

Compiling all the images into a video was the most challenging part of the process.  As I've noted in previous posts, pointing of the camera was both manual and done without an equatorial mount, meaning both Jupiter's position within the picture and the Galilean Moons' orientation around Jupiter changed from frame to frame.

Luckily, I write software for a living and had more than a little training in image processing as a college dork.  Putting the two together, I got the images mostly aligned.  There are some very glaring exceptions.  Almost all of these are due to insisting on taking pictures under non-ideal conditions.  Jupiter and the Galilean Moons are still visible through thin clouds, but either a huge halo emerges around Jupiter (too much light) or the Moons become very dim (not enough light).  Both of these conditions tripped up my automated aligning, forcing me to hand-adjust quite a few frames.  I won't go into too much detail here about the software itself, though I'll post it on Github eventually.

One tip to anyone trying to do the same is don't use generalized computer vision libraries.  Most of them do terribly with backyard astrophotos.  They assume a lot of light and a lot of color and a lot of features.  Until images can fill the frame with the object in question, all of these assumptions are bad for astrophotos.  I converted my images to black/white first (literally black/white, no gray; 1-bit for you computer nerds) to obtain better results than trying to use the generalized computer vision libraries.

I used MATLAB for the image alignment and video rendering.  For the soundtrack, I used some clips I captured on my phone, processed and added to the video in Final Cut Pro.  I considered doing some titling and text overlays, but decided sharing the video was more valuable than perfecting the presentation.  Both MATLAB and Final Cut Pro are pricey options in terms of software.  Octave, Julia and Mathematica are all options to MATLAB, though I've used none and can't attest to the pros/cons of each.  For the rudimentary work I used Final Cut Pro for, iMovie would likely have done just as well.

That's pretty much it.  If anyone has questions or comments, feel free to ask or post in the comments section.