Juno Perijove 44 Options

[Brian Swift]

And discovered GRS also visible in a few departure movie frames.

Images PJ44_92/94/96/98 are rendered from an orthographic view aligned with GRS.
From this perspective the GRS is stretched out relative to the raw image data because of its proximity to Jupiter's limb.
A gamma adjustment was applied to boost contrast.
Half an hour separates each image which were acquired between 2022-08-17T22:00 and 2022-08-17T23:30 at distances ranging from 580,788 to 672,801 km.
Last frame (PJ44_98) shows eclipse shadow of Io crossing over (Sun relative) limb.
Coloration shift between PJ44_92/96 and PJ44_94/98 due to longer exposure causing "over exposure" in some image color bands.

[Brian Swift]

Jupiter, Ganymede on left and Europa on right - PJ44_45 crop

[mcaplinger]

Interesting. So is the 102 bias I see in the raw data a "black level" that is normally present but gets subtracted off before companding?

Yes, all of our "digital CDS" CCD systems going back to the original MS98 MARCI have had this, it seems to be intrinsic to the CCD output. The DC offset has to be compensated for if you use sqroot companding. You can perhaps find indications of this if you look at papers, the PDS docs for MSL and M2020, etc. hard enough (or not.)

Has the current "black level" been used for the entire mission?

Yes, and this image shows that it is unchanged since pre-launch.

Looking at this, if there was a mode that just kept the lower 8-bits (no div 2, no clamping), I think it could be turned back into a
full range non-commanded image, since Jupiters brightness varies fairly slowly.

There's a mode like that for MSL/M2020 though AFAIK nobody has ever used it. There's no such mode for Junocam, which uses a piecewise-linear compander instead of a table lookup compander to save parts and logic in the JDEA.

The reconstruction method you describe might work for a smoothly-lit bland object. The TV system on Mariner 6/7 had a "digital video" stream that consisted of truncated samples like these, but the reconstruction method had problems and the whole concept was generally thought to be a bad idea and was never used again IIRC. https://nssdc.gsfc.nasa.gov/nmc/experiment/...id=1969-030A-01

[Bill Harris]

Thanks, Brian. That view was "stuck between the limb and the terminator" and this is about as good as can be done. It does show some of the structure around the GRS.

--Bill

[Brian Swift]

...
The reconstruction method you describe might work for a smoothly-lit bland object. The TV system on Mariner 6/7 had a "digital video" stream that consisted of truncated samples like these, but the reconstruction method had problems and the whole concept was generally thought to be a bad idea and was never used again IIRC. https://nssdc.gsfc.nasa.gov/nmc/experiment/...id=1969-030A-01

Thanks for the detailed reply.
Fascinating reading about the 1971 Mariner 6/7 image processing in https://www.researchgate.net/publication/23..._and_7_pictures

[Brian Swift]

Thanks, Brian. That view was "stuck between the limb and the terminator" and this is about as good as can be done. It does show some of the structure around the GRS.

Honestly, turned out better than I was expecting given how squished-against-the-limb the GRS is in the raw data.

Here's a quick-and-dirty composite of approach and departure GRS images (PJ44_23/25/27/29/92/94/96/98)

[Brian Swift]

PJ44 Image Collection Exaggerated Color/Contrast

Full Resolution version at https://www.missionjuno.swri.edu/junocam/processing?id=13667

[Brian Swift]

PJ44 Image Collection nominal contrast.

Higher resolution PNG version (where moons are a little more visible) at https://www.missionjuno.swri.edu/junocam/processing?id=13668

[Bill Harris]

Honestly, turned out better than I was expecting given how squished-against-the-limb the GRS is in the raw data.

Here's a quick-and-dirty composite of approach and departure GRS images (PJ44_23/25/27/29/92/94/96/98)

Still, "squished against the limb" gives a different perspective to the GRS.