Juno Perijove 56, November 22, 2023 Options

[mcaplinger]

Some of the images have been posted on missionjuno.

You will immediately notice that there is something weird about them. Yes, we know about this, and I'll say more about it when I can. In the meantime, anything people can do to process them would be appreciated. I've had some success using https://github.com/chunglabmit/pystripe

[Bjorn Jonsson]

The PJ56 images are good enough that I wouldn't make any changes in an attempt to get better images at PJ57 unless there was no risk (or an extremely small risk). And an obvious problem is that the satellite flybys happen very quickly which limits things like extra blue images at longer exposures etc.

The most obvious change to me is to maybe use a different companding function (or modify the current function) in an attempt to increase the dynamic range in the dark areas, especially in the blue channel. I haven't tried applying such functions to test data but an important consideration is the quality of the red images. Improving the quality of the blue images with a different companding function might be a bad idea if it results in worse red images. The PJ56 red images are actually quite good and therefore more important than the blue images.

Another idea is of course to completely omit the companding but that has a major drawback: Increased data storage requirements since the data would be 12 bits/pixel instead of 8. Data compression would probably also be less effective.

[mcaplinger]

Another idea is of course to completely omit the companding...

Alas, this isn't possible. The DRAM subsystem is designed around 8-bit pixels. In hindsight maybe we should have implemented a mode where one could get every other pixel in 12-bit form (there's something similar in CTX and LROC NAC) but obviously we weren't expecting this particular problem.

Similarly, if there's a better companding function that would improve on the current one given all of the limitations on the hardware (described upthread), we haven't been able to come up with it.