On October 10th, Cassini wide-angle camera captured a set of 12 RGB footprints covering Saturn and the rings. Here's an attempt at compositing that data into a mosaic. It's not geometrically accurate, but I tried coaxing the data into at least looking nice.

...and that one's going straight to the blog. Absolutely amazing work with the raw JPEGs, Gordan.

My jaw just hit the floor...amazing!

Holy smokes! I'm speechless. Thank you Gordan for sharing.

Wow! That's the sort of view I've dreamed I would only ever see in a science fiction movie or if we had somekind of amazing futuristic spacecraft orbiting around that distant ringed planet....WAIT! We do!

Aaaand that's a new desktop...

Really great!

Amazing Gordan!

If you don't mind me picking your brain, just how do you go about combining the night-side hemisphere with the sunlit part of the disc? HDR merging or your own special sauce?

This was my attempt at working with the Clear-filtered frames:

http://postimg.org/image/w3qnpzhtl/full/

Ian, I simply assumed the original data used 12bit encoding mode used so the JPEG DNs are basically linear (a reasonable, but not 100% accurate assumption when uncalibrated images are concerned) as it looked that way to me and the color profile I use in Photoshop (and the one I use for calibrated data that is linearized by default) automatically adjusts that to the sRGB 2.2 display gamma. The nightside was heavily noise-reduction filtered to reduce blocky artifacts, though.

I just posted about it as well, with a description of some of the sights. Gordan, this was an AMAZING piece of work! And Emily, thanks for linking to it; I saw it first in your tweet and blog. I credit you, of course.

http://www.slate.com/blogs/bad_astronomy/2..._ugarkovic.html

[Sorry to misspell your first name in the URL!] My favorite part (besides the steep angle lowering the usual elliptical appearance of the rings) is seeing Prometheus and Pandora to the upper right of the F ring. Astonishing, on this scale.

Oh My! That is astonishing. New desktop here as well.

"looking nice" is the understatement of the century. That is a stunning. breathtaking image. Incredible work.

Any chance of sending me the uncompressed master of this? This would be ideal for animation sequence in the film due to its resolution

You're on Slashdot too (and so is this thread).
http://science.slashdot.org/story/13/10/17...n-all-its-glory

Whoa, Phil, good eye. That really is amazing.

Agreed. Gordan sent me a lossless version of this for use in the film and I'm mulling over it if I can connect it to some of Cassini's closer view of Prometheus and Pandora. I will have to look closely at my raw archives. There is some stuff here but not sure if 100% will match up: Cassin Raw image movie.

I just looked at this on my cheap 50" Seiki 4K UltraHD I have hooked up to my main desktop. Pretty staggering at full resolution. Can't wait to see this on a 8-story high screen.

The mosaic is the Image of the Day at NASA: http://www.nasa.gov/mission_pages/cassini/...rn20131017.html

You're a celebrity in space circles now

I like doing RGB stacks from Cassini, but I don't know how to calibrate colours (rather than adjust them arbitrarily until they resemble "true colour"), so my Titan appears white with vivid blue haze, and my Saturn is bluish-yellowish-grey. But Saturn's atmospheric features are more prominent.
Click to view attachment

Today in the paper. Not bad at all Gordan!
(might need to mirror the image )

MOD NOTE: Edited to remove political comment.

Congratulations, Gordan... breathtaking image!

Gordan,

Many thanks for the explanation: the first thing I indeed noticed was the difference in gamma between your composite and my attempt at the clear-filtered mosaic. With regards to the JPEG DNs, how would you tackle a raw you suspect of being an LUT-converted 8-bit image? Trial and error? Or is there a way to approximately reverse the conversion?

Thanks again.

I haven't found a reliable way to handle the LUT-encoded stuff which makes up for the majority of Cassini imagery. It's mostly trial and error. I found it's more difficult to do mosaics as well. Theoretically, the LUT uses a square root encoding slope so if you wanted to "linearize" it, you might want to apply a 0.5 gamma (working in 16 bit depth at all times, of course), but I found that doesn't work out nice.

The good thing about the LUT encoding is you don't really have to linearize it, it's pretty close to an inverse of the default sRGB gamma so simply loading the raws into RGB channels in any vanilla photo editor and you're pretty much good to go (assuming the histogram stretch didn't massively clip dark and bright levels).

I have not done this yet but a curves preset could be build from a LUT if someone is up to the task: Photoshop curves to LUT It would be a reverse of this process.

It would be a simple enough task if it wasn't for the raw histogram stretch automatically applied on the ground. Once that's done, you have no idea what original level was mapped to Jpeg DN 255, likewise for DN 0. This is what, I think, makes matching brightnesses between separate frames and mosaic footprints in LUT mode difficult. Too many degrees of freedom involved. You have the one-size-fits-all Photoshop levels curve at your end, but the actual flight LUT curve was stretched an unknown amount by the ground histogram stretch. Convolve those two and you still end up with nonlinearities.

For 12 bit stuff, especially if it shows some black space so the stretch leaves it alone, you basically have just one thing to play with - brightness.

I was under the impression that the amount of stretch was in extra lbl calibration data - or am I confusing this with SDO? We've been working with so much data lately. Kevin McAbee, the other key volunteer on the film, has been working on Cassini to automate processing of the raw files. I can check with him too.

There is no camera metadata available for the Cassini raw images that I'm aware of. For PDS archived stuff this is not an issue, of course.

I'm pretty sure you are right, I don't recall seeing it either, I think that is only SDO (which has it's own sets of problems and is actually much harder to deal with). I poked around in some of my data stores and don't see anything except from PDS.

Wow... this is awesome, especially when keeping in mind that it's from JPG data and not PDS files.

And the mosaic using the science quality images

http://photojournal.jpl.nasa.gov/catalog/PIA17474

Honestly - I prefer ugordan's

Yeah, the official one is, err, really yellow.

Agreed, not as asthetically pleasing as Ugordans. The photojournal site linked to a couple of posts above does however say that the image 'is as human eyes would see it'. This sounds to my untrained ears like a fairly bold statement.

The official one is a bit disappointing. Some very bad joins, the F-ring is almost completely gone and the two small moons have disappeared.

thanks ugordan - my desktop is now complete!

All these observations about the shortcomings of the official release (however accurate or otherwise) are, IMHO, violations of rule 2.6.

Suggesting that an official release image could have been done better or that another version is better I don't see how this fits into the prerequisite for 2.6, namely "When mentioning scientists, engineers, or other mission personnel..." - there is no such mention. If it turned into accusations of incompetence and such, I would see it differently, as that would be an implicit mention. That said, we should give it a rest, as points have been made and continuing on this route is, I would agree, in poor taste.

Taking the thread on to less controversial ground, here are a couple of rings movies; the second in particular shows two, maybe three, ghostly 'blink-and-you'll-miss-them' spokes, plus the eccentric Huygens Ringlet stands out by virtue of its inherent 'wobble':

The Rotating Rings of Saturn (October 19, 2013)
http://www.youtube.com/v/42NRH-LNonQ&hd=1

The Elusive Spokes of Saturn (October 22, 2013)
http://www.youtube.com/v/O4wn81eI2lw&hd=1

Great stuff Ian - very nice work. How many frames per second are the masters of these?

Was thinking these might be really fun with some Phillip Glass type music.

Thanks! All I did was tween the original 58 frame sequence from 8fps to 16fps.

It is interesting that in addition to the hexagonal gray area very close to the pole, some of the other demarcation lines all the way out to the white cloud bank at about 30 degrees also appear to be composed of straight segments approximately equal in length. Certainly the gray hexagon is nested in a slightly offset brownish polygon; the others require more imagination. Excuse me if this is either trivially obvious or a patent hallucination.

Cassini website has now a new area "Amateur Images", where your excellent mosaic is featured: http://saturn.jpl.nasa.gov/photos/amateurimages/
along with an image by yours truly (Titan)