Super-resolution challenge, Help requested by the science team |
Super-resolution challenge, Help requested by the science team |
Nov 3 2008, 11:11 PM
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#16
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
Here's a flicker gif between a single frame and manual stack in Photoshop of the 12 frames, just for fun:
Magnified 2x from original pixel scale. Most likely much better than this can be done. If anything, the many frames allow heavier deconvolution/sharpening to be performed. -------------------- |
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Nov 4 2008, 12:14 AM
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#17
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Member Group: Members Posts: 699 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
Nice! It looks like you did some sharpening- what kind of sharpening?
John. |
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Nov 4 2008, 08:40 AM
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#18
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
I used the Smart Sharpen filter in Photoshop, using the "more accurate" lens blur removal. It produces tighter (and noisier) results than simple unsharp filtering. It's hard to force oneself not to overdo the sharpening, but in this case I do believe it brings out details that aren't resolvable in single frames.
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Nov 8 2008, 09:59 PM
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#19
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Member Group: Members Posts: 128 Joined: 10-December 06 From: Atlanta Member No.: 1472 |
Here is the effect of subpixel shift-and-add on the dataset. The image on the right is the first raw image, enlarged twice and unsharped. To make the one on the left, all the raw images are scaled x8, then the amount of shift for each one compared to the first image (in the x8 setting, i.e. 0.125 pixels resolution in the original dataset) is found and they are co-added taking into account the shift value, and finally the co-added image is rescaled to x2 and processed using the same unsharp filter as the one applied to the image on the right.
The main difference in that unsharping introduced lots of noise to the raw image, whereas the processed image tolerated it much better and some previously unseen features are now detectable. |
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Nov 10 2008, 08:41 PM
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#20
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Member Group: Members Posts: 699 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
Thanks to both ugordan and siravan for those images! We're also interested in what can be done with a smaller number of images, 4, for example. Could you try the same thing using just four of the input images?
Thanks, John. |
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Nov 13 2008, 09:54 AM
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#21
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Member Group: Members Posts: 293 Joined: 22-September 08 From: Spain Member No.: 4350 |
I had to try.
2x I used 5 images plus one to reduce noise. Mostly was about scaling up without interpolation, aligning the images, do some blending and several steps of gaussian blur and unsharp mask before scaling down --all very empirical. A real pro should be able to do better. |
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Nov 13 2008, 01:07 PM
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#22
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Here is my take. I have versions with 4 frames, 6 frames, and 12. First, I deconvoluted the images to combat the broad PSF. I then blew the images up to 5x and sharpened them based on the new artificial point spread the enlargement created. I selectively stacked them, weighting them based on quality (I could probably do a bit better, but I was trying to hurry). After merging the image, I applied a light round of deconvolution based on a 4 pixel PSF and then reduced the images to 1.9x. A slight bit of sharpening was applied at this point.
4 Frames 6 Frames 12 Frames -------------------- |
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Nov 14 2008, 05:00 AM
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#23
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Here is a view of Triton when it was 120 pixels across (shown here at about 2.5x). The inset shows two apparent plumes visible near the bottom of the terminator.
Now that I have worked on the Ganymede stack, might I ask if the image used is the NH frame from the same angle or generated from something else? The reason I ask is that the detail cutoff seems a bit odd compared to the Triton set and other real sets I have worked on. Namely, the technique does much better with high contrast details than low contrast details for obvious reasons. With the Ganymede images, the cutoff seems even. If it is from the lone NH frame, the reason is simple - I am smacking into the resolution limit of the image. -------------------- |
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Nov 15 2008, 04:22 PM
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#24
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Member Group: Members Posts: 699 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
This is a synthetic image using a Galileo photomosaic, but generated with the same geometry as the best New Horizons Ganymede image (for reasons that seemed like a good idea at the time).
Very interesting Triton image- that plume looks fairly convincing! It's a good analog for what we might see on approach to Pluto, where the approach phase angle (15 degrees) is similar. John. |
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Nov 19 2008, 01:23 PM
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#25
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Newbie Group: Members Posts: 10 Joined: 20-October 08 From: Romania Member No.: 4461 |
I'll take the challenge...I only hope that I'll have some results before NH reaches its target ...
-------------------- If you see me posting monday to friday between 8 a.m. CET and 6 p.m. CET, chances are I'm at work... not doing my job!
If you see me posting outside this interval, chances are I'm at home... and should really be working for my PhD! |
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Nov 20 2008, 01:34 PM
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#26
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
This is a synthetic image using a Galileo photomosaic, but generated with the same geometry as the best New Horizons Ganymede image (for reasons that seemed like a good idea at the time). I figured out what the issue is. Most stacks I have worked with include some severely underexposed images. However, the well exposed images were more likely to be smeared because of the longer exposure time. Hence, the high contrast features (the ones visible in even the underexposed but very sharp images) ended up looking better than the fainter features. Given the nature of LORRI (not having color filters), the image sets it produces will likely be more like the Ganymede sample than what I am used to. -------------------- |
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Oct 16 2009, 04:43 PM
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#27
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Junior Member Group: Members Posts: 94 Joined: 15-October 09 Member No.: 4979 |
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Oct 16 2009, 04:45 PM
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#28
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Junior Member Group: Members Posts: 94 Joined: 15-October 09 Member No.: 4979 |
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Oct 16 2009, 04:51 PM
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#29
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Junior Member Group: Members Posts: 94 Joined: 15-October 09 Member No.: 4979 |
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