Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff Options

[Bjorn Jonsson]

Thanks to modern computers and software the old, 'official' Voyager Jupiter images can be reprocessed into something much better. There is also a lot of Voyager data there that was never processed into color composites and/or mosaics (or at least it has not appeared on the WWW). With proper processing the apparent image quality approaches the quality of the Cassini images but needless to say the wavelength coverage is (vastly) inferior.

I have recently been taking a close look at the high resolution Voyager 1 images, i.e. the images obtained in early March 1979. This is going to result in some new and/or reprocessed mosaics. The first one is now complete and I'm working on another one.

The image below is a 12 image mosaic (12 orange + 12 violet + 12 synthetic green images). The images were obtained on March 2, 1979 at a range of 4.3 million km. The first image (C1629045.IMQ) was obtained at 05:09:23 and the last one (C1629131.IMQ) at 05:46:11. The resolution is roughly 43 km/pixel.



The raw images were calibrated, reprojected to simple cylindrical projection, mosaicked and then rendered using a typical viewing geometry (there is no such thing as a "correct viewing geometry" because the images were obtained over a 37 minute period with Jupiter rotating). I then fixed the color balance. I still haven't 'standardized' how I process the Voyager color. I wasn't completely satisfied with the color I got using an approach similar to what's described in another thread but I think the color could be improved a bit. The final step was to sharpen the resulting image a bit, mainly to compensate for all of the resampling that the previous processing steps required.

This image shows lots of features: The Great Red Spot and one of the three white ovals present during the Voyager flybys, smaller spots, scallopped belt/zone boundaries, gravity waves, a bright equatorial plume and the dusky south polar region.

I don't think I'm bragging by saying that this is probably the best Voyager 1 Jupiter mosaic that I know of, mainly because of its size (12 images).

I will be posting more Jupiter stuff in this thread in the coming days/weeks, both mosaics and interesting images (and needless to say, others are welcome to post images and mosaics as well).

[machi]

GRS from Voyager 1.
Resampled at 5 km/pix, original resolution around 5.5 km/pix.
Color from wide angle images (violet, green and orange filters).

Attached thumbnail(s)

 

[Astro0]

OMG!

[Stu]

No, sorry, I don't believe it. You've given yourself away this time.

Clearly you have a TARDIS, allowing you to travel back in time and photograph the GRS out the TARDIS door using a state of the art 21st century camera...

Seriously, that's a stunning image, well done!

[ElkGroveDan]

Holy smokes. Maybe it's just my mind interpreting color shading as shadows. But that now really has the appearance of a vortex cutting deep into the upper cloud layers.

[Hungry4info]

Wow. Nice!
That's very impressive!

[machi]

Stu:
I think, that even with TARDIS, I would be cooked by radiation .

Dan:
If I remember correctly, then darker areas are widely recognized as deeper atmospheric layers (in some cases, it can be actually seen).
And I think that darker areas near small clouds are really their shadows.

[Ian R]

Hot Diggity Dog! That's marvellous Daniel... another APOD-worthy effort!

[Ian R]

Nice, both the images and the videos. I can appreciate how labor intensive a video with that many frames can be, you had to have a *lot* of will power to do that I imagine.

Do you use calibrated or raw data?

Gordan,

I'm pretty capricious when it comes to projects like these, so I tend to start working on them purely on a whim, and then before I know it, I feel obliged to follow them through to their conclusion. Unfortunately, I'm using the raw data, which has proved to be troublesome, due to the geometric distortions that are present in the frames.

I originally started with the Green filter movie only. Then I figured out how to semi-automatically create colour frames using the Python macro/scripting feature in Paint Shop Pro. It works very well, and means that I can essentially create a fairly-well aligned colour frame with only a few clicks of a mouse:

http://www.youtube.com/watch?v=0XjW0vZZZXw

[ZLD]

I took the image and did my own processing on it; great work by the way Daniel. I was able to bring about a bit more depth and I would certainly have to agree that this image definitely makes the case for the GRS being deeper than I had ever imagined. The first image shows my processing and makes it clear the depth of the cloud layers. Most interesting is the white swooping layer at the far left of the image; it appears to even cast a shadow on a large portion of the GRS.

Am I just seeing things or is this really a many hundreds of miles in difference from that top layer to the ones next to it?

(admin note - it's best not to put images straight into a thread like that - we've changed them to links.)
-I apologize for the error. I hadn't meant for them to be fullsize thumbs.

Edit: I hadn't ever posted this one either. This is probably bordering on false-color but it shows greater depth to the GRS area from Bjorn's image.

[Astro0]

ZLD, my take is that your 'shadow' is in fact the variance in brightness between several images that Machi has stitched together and not an effect produced by higher cloud layers as suggested by your red lines. I'm sure that Machi could confirm this. Also, I'd suggest that the light is coming from the 'right' of this image (of course by 'right', I mean a few hundred million miles/kilometres away).

[machi]

ZLD, Astro0:

Yes, "shadow" is variance in brightness between images. Voyager took two complementary sets of images with green and violet filters.
I used green filter images for high resolution mosaic and violet images for filling remaining gaps. But violet images are really different from
green images, so this variance can be seen. You can actually see depths of layers in some cases, but this isn't one of them.
I'll try post some example.

[machi]

It's possible use both green and violet images for high resolution color mosaic of GRS, but at the cost of limited coverage.
I create this image as demonstration, how good this can be (and how excellent is quality of 70's Voyager images).
Color is created from green, violet and synthetic images. Resolution is original (~5.5 km/pix). Contrast is exaggerated.
Interesting feature is something, what looks as entrance of horizontal tromb (horizontal funnel) in the left image.

Attached thumbnail(s)

 

[ZLD]

That is quite impressive. Can you send me a link to the raw data you are using to output these images? I've looked several times in the past and come up empty handed. I'm somewhat new to processing space imagery but somewhat experienced in processing photos in other areas. Any tips and sources for photos, especially those from the voyager missions I'm interested in.

[elakdawalla]

My favorite search tool for Voyager and other outer planets images is now OPUS at the Rings Node, but the Atlas at the Imaging Node is also good.

[machi]

ZLD:

I have almost all image data from Voyager downloaded on CD's, which was perhaps my first activity, when I started with internet .
You can download (almost) all data from here:
http://pds-imaging.jpl.nasa.gov/resources/onlineData.html

These images aren't calibrated and geometrically corrected.
Some data are in calibration process and calibrated data are available from here:
http://pds-rings.seti.org/voyager/iss/calib_images.html

You can open original images (*.imq) with Voyager Image Viewer (which has browse capability), Nasaview or img2png.
Calibrated data are more difficult to opening. You can open them as raw data.