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Super-resolution challenge, Help requested by the science team
john_s
post Nov 1 2008, 12:16 AM
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Greetings:

Here's another chance to maybe help out the New Horizons science team! We are planning the Pluto imaging sequence, and are considering the best strategy for squeezing the maximum resolution out of our images, including "super resolution" techniques, particularly for the side of Pluto that faces away from us at close approach, which we will see with a disk diameter of only about 120 pixels in our high-resolution camera LORRI. As some members of this forum have done impressive work with super-resolution processing of MER images, maybe you can try your hand with some synthetic "Pluto" images to see what the potential is? This may be more challenging than for MER, because our PSF is relatively broad, about 2 pixels wide.

We want to know how many images to take of a given face of Pluto to get maximum benefit from super resolution techniques, if indeed they are useful at all.

I plan to generate a bunch of synthetic images with slightly different pixel positioning and smear, and with realistic noise levels, and then make them available for experiments to see how well they can be combined and sharpened to improve the resolution.

If you are interested in giving this a shot, let me know. Also let me know if you can work with 12-bit or 16-bit images, and if so what format is most convenient. I can easily make 16-bit FITS files, for instance. It may be that 8-bit PNGs will be adequate, too.

Thanks,
John.
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tedstryk
post Nov 1 2008, 02:33 AM
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I am definitely interested. I will say this. Although some sets showed some improvements with just three or four images, it starts to reach its peak around five or six images. Beyond about 10 images (I am basing this on MER and Pathfinder) and there isn't any real improvement. I have worked a little with deconvoluting some of the images of the Galileans, but there are of course no sets to stack. I don't know how such images would work in a super-res sequence, but it is definitely worth a try.


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john_s
post Nov 1 2008, 03:25 AM
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Cool! Tell me your preferred image format.

John.
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tedstryk
post Nov 1 2008, 12:47 PM
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QUOTE (john_s @ Nov 1 2008, 04:25 AM) *
Cool! Tell me your preferred image format.

John.



While 16-bit tiff files might have some improvement, I am not so sure it would be significant when compared to a 12-bit file. The greater bit depth might help with the low contrast features, but it is hard to say for sure - A lot depends on LORRI and whether there is real information in the images that could be better plucked out of 16-bit images. I suspect that 12-bit imaging would be adequate. 8-bit would suffer a lot, especially given the fact that they would have to be deconvoluted to reduce the effects of the wide PSF.


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john_s
post Nov 1 2008, 03:00 PM
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So do you prefer TIFF files? If so, I have to figure out how to make 12- or 16-bit TIFFs. If you can read FITS files (or 16-bit PNGs) we're all set, though.

John.
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tedstryk
post Nov 1 2008, 03:04 PM
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QUOTE (john_s @ Nov 1 2008, 03:00 PM) *
So do you prefer TIFF files? If so, I have to figure out how to make 12- or 16-bit TIFFs. If you can read FITS files (or 16-bit PNGs) we're all set, though.

John.

Yes, I can read FITS files.

Ted


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john_s
post Nov 1 2008, 04:19 PM
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Great, here's a file with 6 simulated images of Ganymede in 16-bit FITS format. I'll send another six in my next mail.

Attached File  superresolutiontest1.zip ( 649.71K ) Number of downloads: 404
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john_s
post Nov 1 2008, 04:27 PM
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And here's the other six...

John.

Attached File  superresolutiontest2.zip ( 650.01K ) Number of downloads: 357

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john_s
post Nov 1 2008, 06:46 PM
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Oops, there's a bug in those image sets- they are variably smeared (at a realistic sub-pixel level), but the image *positions* don't vary randomly at the pixel level as they should. I'll fix the problem and re-post when I can- in the mean time the current image sets should be good for practice.

John.
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tedstryk
post Nov 1 2008, 06:58 PM
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As far as stacking goes, these might be interesting. Without position variations, there will be no super-res effect. I have a real test question. It also might be interesting to take a test sequence using Saturn.


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siravan
post Nov 2 2008, 10:07 PM
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QUOTE (john_s @ Nov 1 2008, 11:19 AM) *
Great, here's a file with 6 simulated images of Ganymede in 16-bit FITS format. I'll send another six in my next mail.

Attached File  superresolutiontest1.zip ( 649.71K ) Number of downloads: 404


Here is my first pass on the data as a practice for the actual test. Of course, as there is no shift in the data set, no superresolution effect in expected. The images are enlarged four times, stacked together and then unsharped. The main effect is improved SNR by stacking which allows for a more aggressive high-pass filtering.

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john_s
post Nov 3 2008, 09:10 PM
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OK, here's a new and improved set of six FITS files- they are now shifted randomly as well as having random smear at the levels expected for the actual LORRI images (typically ~0.7 pixels).

The other six will follow next.

John.
Attached File  lorrirestest1_fits.zip ( 634.54K ) Number of downloads: 347



And the next six...

Attached File  lorrirestest2_fits.zip ( 634.44K ) Number of downloads: 345

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john_s
post Nov 3 2008, 09:15 PM
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Not sure why those two ZIP files ended up in the same message...

Anyway, here are the first 6 images in 16-bit PNG format in case that's easier to read. I've added a bias of 20 DN to the PNGs, to avoid negative numbers (there are some negative sky values in the original images, due to random noise).

John.

Attached File  lorrirestest1_png.zip ( 536.32K ) Number of downloads: 331

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john_s
post Nov 3 2008, 09:19 PM
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And the rest of the images in PNG format...

Attached File  lorrirestest2_png.zip ( 535.53K ) Number of downloads: 332

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john_s
post Nov 3 2008, 09:24 PM
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By the way, the PSF in these simulations (not counting the motion smear) is a Gaussian with a 2-pixel FWHM, in case you want to do some deconvolving. That's fairly close to the actual LORRI PSF, though not a perfect match.

John.
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