[X] My Assistant

[Brian Burns]

Hello,

I'm a bit new here - I recently started on a project which I thought would be fun, to assemble movies of all the Voyager flybys. Of course, with 70k+ images, it would have to be automated as much as possible, and the results would be fairly crude. But there's enough information to make some rough black and white and color movies with one segment per target, and eventually combine them all into one movie.

The main task is getting the images properly centered, since the cameras don't point right at the target - there are still some jitters at the moment, so it needs some more stabilization. But in any case, here are some slightly bumpy rides along with Voyager - these are from versions 0.3-0.34 -

Ariel (Uranus)
https://www.youtube.com/watch?v=HeGgH34v8R4

Uranus
https://www.youtube.com/watch?v=0RLGadmvc40

Neptune
https://www.youtube.com/watch?v=HlU2_NOgoew

Assembling a color movie is a matter of combining the images that seem to go together (since it's not explicit in the data) - this is a first attempt at that. There are frames that lack certain channels, so colors are pretty off at points - later it could borrow a nearby image when a channel is missing.

Neptune, colorized
https://www.youtube.com/watch?v=c8O2BKqM0Qc

The goal is to generate the movies with as little manual annotation as possible - there are parts that need it though, like handling images with multiple targets, slowing down the movie at certain points, and turning off the centering at closest approach.

Anyway, just wanted to share what I've got so far - hopefully one day it will be able to make a nice, stable movie of all the flybys, with some appropriate music. Once the code is a little more stable I'll post the project on GitHub - it's written in Python with OpenCV, SciPy, and IMG2PNG.

-Brian

[Astroboy]

Do properly calibrated Voyager images have a correct, intended brightness, or just a correct brightness relative to other Voyager images? The way I've been processing them into color has involved contrast stretching the brightest image and applying an identical stretch to the other, relatively dimmer images of the same target. When I apply the same stretch to Titan as I would to Saturn, Titan appears very dim, as it should be relative to Saturn.

Also, is there a correct way to balance the colors in a false color image? UV images of Jupiter are pretty dim relative to the visible light images... do those UV images have to be brightened?

[Brian Burns]

I've just been constrast stretching every image as bright as it can go, which I'm sure is wrong... the colors of the composites are often odd looking, e.g. Io (though the approach and rotation movies of Jupiter, Uranus, and Neptune look okay, I think). Good idea though to apply the same stretch to every image, wish I had thought of that.

At the moment the channel weights would need to be tweaked manually, so there needs to be a more automatable way to balance the colors. I was thinking of having a reference image for each target with good colors, then adjusting the channel weights to try to approximate the correct spectrum. This would be nice for Neptune, e.g., since then you could colorize the movie to match the nicest blue images.

But I don't know about the UV filter - those images are pretty dim. I guess it depends on what you want it to look like?

And the other problem with brightening images is the areas in the corners that are sometimes whited out, or other noise in the image - they throw the contrast stretching off. I'd like to automate ignoring those hot pixels somehow also as there are a lot of those images scattered around. Something about there being a big gap between the brightest pixels and the mass of the rest of the histogram - will have to fiddle around with that.