[X] My Assistant

[Guest_BruceMoomaw_*]

You know, I hadn't thought of that, but I suppose deconvolution could be applied fairly easily to those Lunar Orbiter 1 photos from its high-resolution lens that were smeared because the orbital image-motion compensation system was interfered with by that lens' shutter. The blurring in that case was just in one direction. (But then, they only took a few photos with it before sensibly using the medium-resolution lens for the rest of the mission.)

Somewhere, on one of those big pictorial brochures that the New Horizons team has released, there's an "original" version of Hubble's Pluto photos that show just how jagged-looking and "Cubist" those photos are before they're deliberately smoothed-up for public consumption. The situation won't be as bad for Hubble's photos of Ceres and Vesta; but still, as I say, deconvolution programs simply can't and don't do any good at all for any of Hubble's photos after its mirror was corrected. You're wasting your time on those.

[edstrick]

The problem with trying to deconvolve the image-motion-smeared Lunar Orbiter 1 pics is that the smear is large.. tens to hundreds of pixels, and the data is horribly non-quantitative with horrendous levels of readout and analog-transmission and recording artifacts. You'd end up enhancing artifacts, not restoring details, I am pretty well convinced.

More useful to try to restore are the Orbiter IV images that were literally fogged by condensation on the camera box window when they had problems with the aperture door sticking open early in the mission. There was variable amounts of patchy condensation on the window surface and many images from the first quarter to third of the mission were SEVERELY degraded.... basically everything from Tranquilitatis or Serenetatitis to the east limb and a bit beyond.

Remember, the film was developed on the spacecraft by a "wet bimat" process... sort of like the film and polaroid processing that produced b&W negatives... so there had to be moisture in the camera and film cannister.

[tedstryk]

Somewhere, on one of those big pictorial brochures that the New Horizons team has been released, there's an "original" version of Hubble's Pluto photos that show just how jagged-looking and "Cubist" those photos are before they're deliberately smoothed-up for public consumption.  The situation won't be as bad for Hubble's photos of Ceres and Vesta; but still, as I say, deconvolution programs simply can't and don't do any good at all for any of Hubble's photos after its mirror was corrected.  You're wasting your time on those.

It depends on the type of source. For point sources, and other high contrast sources, it works pretty well. But for extended, low contrast sources, it can do little. Also, it works better with WFPC (those Pluto images are FOC), because due to its lower resolution, the problems don't spread light over as many pixels.
This is a commonly seen HST Mars image from 1993 (this is my version).


However, much of the bluring in this deconvolved image is due to the fact that it is enlarged. Here is the image at original resolution:



Also, a lot of difficulty in processing this is that the rotation of Mars between images is TERRIBLE.

[Guest_BruceMoomaw_*]

An original Hubble image of Vesta showing the pixel graininess is at http://hubblesite.org/newscenter/newsdesk/...1997/27/image/d . It's obviously much better than Hubble's best Pluto views -- which can be found on page 15 of http://pluto.jhuapl.edu/overview/deis/pres...esentations.pdf -- but you can still see that the value of deconvolution would be very small.

[Harry]

Once again: while I hate to say it, to the extent that these Huble images are fuzzy due to a simple shortage of pixels rather than to actual defocusing of the telescope's mirror, you're engaged in a fool's errand -- your program will just be synthesizing nonexistent details.  And the Hubble images of little tiny distant bodies like Vesta and Pluto are indeed seriously limited in their pixel width -- those smooth-looking views of them that are published are misleading, being themselves the product of computer programs designed to make the original images look much less "grainy".

Oh, please don't think it too seriously. I've not intended to report some scientifically rigid results here, but just have proposed a possible way to guess the features of Vesta...

[Guest_BruceMoomaw_*]

OK, but if it doesn't actually give us any information on real features it is -- to put it mildly -- an idle hobby.

[mike]

Just say you're making art..

[Harry]

The image of Vesta taken by HST (left) and its de-convoluted image (right) processed by Focus Corrector (focus depth:=4, iterations:=9)

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[The Messenger]

OK, but if it doesn't actually give us any information on real features it is -- to put it mildly -- an idle hobby.

We used to get in this argument a lot, when evaluating X-ray deconvolution schemes. If the material being evaluated was well known and characterized, there are sub-pixel routines that will truly improve resolution. However, if there are unknown contaminates, and expecially contaminates of the same size as the pixels, these routines actually remove information.

[Harry]

Although it is not the picture for asteroids, I attached the de-convoluted image processed by Focus Corrector as a reference. (left: original image of Supernova 1987A, right: its de-convoluted image)

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[Harry]

The image of Callisto taken by HST (left) and its de-convoluted image (right) processed by Focus Corrector (focus depth:=2.4, iterations:=5)

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[Harry]

The image of Io taken by HST (left) and its de-convoluted image (right) processed by Focus Corrector (focus depth:=2, iterations:=7)

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[ugordan]

The image of Io taken by HST (left) and its de-convoluted image (right) processed by Focus Corrector (focus depth:=2, iterations:=7)

This would be an excellent time for someone with the know-how to render an Io view of the same spatial resolution and central coordinates from the Galileo data so we could actually compare how well the features match up.
Any volunteers?

[JRehling]

This would be an excellent time for someone with the know-how to render an Io view of the same spatial resolution and central coordinates from the Galileo data so we could actually compare how well the features match up.
Any volunteers?

If valiadating the approach is the point, an easier exercise would be to downsample some images, let him run his magic on them, and see if the details in his results correlate with the original. For example, take a 1000x1000 image of the Moon, shrink it to 100x100, then re-enlarge the shrunken version to 1000x1000, and see if Harry's algorithm recreates real features smaller than 5 pixels in the original. If not, then the details should be considered fiction.

That would be easier than trying to project Io imagery. The HST images of the Galileans, if the unusual colors are any indication, did not use the same (or even similar) filters as Galileo.

[Airbag]

If valiadating the approach is the point, an easier exercise would be to downsample some images, let him run his magic on them, and see if the details in his results correlate with the original. [...]

No, that is not the same at all - you can't create information when it is not there to begin with.

Deconvolution works when trying to correct an image that has undergone convolution, e.g. because of the effects of diffraction limited optics. Deconvolution will then attempt the reverse mathematical process to "undo" the original convolution. Of course, in all image processing operations, some information is lost - it is just a matter of what kind of information you want to optimise at the expense of others.

Note that deconvolution only really works if you know the specifics of the original convolution process, e.g. the spherical abberation of the HST's main mirror. If you just apply some random deconvolution until you start seeing things, you probably just are.

Airbag