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Deep Impact camera data, Messing about with images from the PDS
ugordan
post Dec 28 2009, 11:42 PM
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QUOTE (elakdawalla @ Dec 29 2009, 12:09 AM) *
Sorry, Gordan, I meant OGB! I fixed that in my posts above.

I fixed the derived image as well, based on the fact it's a blue channel. The MRI and HRI images now do look pretty darn similar.


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machi
post Dec 29 2009, 12:04 AM
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"per partes". First rough match of the color and BW image is done (color image is resampled and rotated), than misfitting parts are removed and replaced by more suitable resampled version of the color image (mostly same image).
This is simplest and quickest way, when images are similar. More sophisticated is warping, but I don't know, if this feature is in the Photoshop. But It is in ImageJ.


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ugordan
post Dec 29 2009, 04:11 PM
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QUOTE (machi @ Dec 29 2009, 01:04 AM) *
This is simplest and quickest way, when images are similar.

I do that sometimes as well. Warping the images in Photoshop (or any geometric operation for that matter) lowers image sharpness so I tend to avoid it where I can.

QUOTE (machi @ Dec 29 2009, 01:04 AM) *
More sophisticated is warping, but I don't know, if this feature is in the Photoshop.

It's available in Photoshop, but (at least in CS2) you don't get many control points so the feature is of limited use when you want tight control like in the example above.


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tedstryk
post Dec 29 2009, 05:19 PM
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I will often work with images at 5x...that significantly reduces the impact of warping.


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ElkGroveDan
post Dec 29 2009, 05:40 PM
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QUOTE (machi @ Dec 28 2009, 02:28 PM) *
Here is colorised ITC image (color from your O-G-V image).

I could stare at that image all day. Does anyone have any idea of what quality of images we will be seeing from NExT/Stardust? There is a mockup here but my recollection of Wild 2 images was that they were problematic from the volatiles contamination issue which was never entirely resolved.


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elakdawalla
post Dec 29 2009, 06:04 PM
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For context, here's what the raw images from Stardust at Wild 2 looked like.

http://www.planetary.org/explore/topics/as...2_stardust.html

Stardust will get slightly closer to Tempel 1, which is about double the diameter of Wild 2. So in theory we should get better pictures of Tempel 1 than we got from the MRI, but not as sharp as the ITS, and there's no color capability.


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tedstryk
post Dec 29 2009, 06:10 PM
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Stardust's camera is a spare Cassini WAC, so it is quite good.

I don't understand what all this attention to color is about unless we are talking about bringing out extreme minutia to study composition. Based on everything I can tell via HRI, we are dealing with something that is essentially colorless. Other than tweaking out the overall hue of the scene, I don't see much to do.


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ugordan
post Dec 29 2009, 06:29 PM
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QUOTE (tedstryk @ Dec 29 2009, 07:10 PM) *
I don't understand what all this attention to color is about unless we are talking about bringing out extreme minutia to study composition.

To each his own, I guess.

QUOTE
Based on everything I can tell via HRI, we are dealing with something that is essentially colorless. Other than tweaking out the overall hue of the scene, I don't see much to do.

It's not completely colorless uniform in color - those white patches for example stand out on this hemisphere. For me personally, simple colorizations often don't pass the sniff test in that they look more fake to me than original monochromatic data. In such cases I'd rather have the original grayscale representation.


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tedstryk
post Dec 30 2009, 03:34 PM
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QUOTE (ugordan @ Dec 29 2009, 06:29 PM) *
For me personally, simple colorizations often don't pass the sniff test in that they look more fake to me than original monochromatic data. In such cases I'd rather have the original grayscale representation.


That often has a lot to do with poor saturation modeling.


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ElkGroveDan
post Dec 30 2009, 04:32 PM
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QUOTE (tedstryk @ Dec 30 2009, 07:34 AM) *
That often has a lot to do with poor saturation modeling.


That is definitely true with colorings of images back on the home planet, contrast too. People have a tendency to jack up color contrasts way beyond what is reasonable. With this or any art whether it's writing, or carpentry or anything you spend a long time working on, I find it's best to put the job away for a while then come back a day later and ask yourself what jumped out at you when the project was reopened.

I think Gordan's issue is probably is with "blanket" color efforts where a single color is draped over a large section of an image. A really good colorist (did I just make that up?) will apply subtle hue and saturation variations based on variations in image density that are woven or spotted through a section that might otherwise be treated as one color. There's one person here at UMSF who is a master at it.


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DFinfrock
post Dec 31 2009, 02:03 AM
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QUOTE (ElkGroveDan @ Dec 30 2009, 04:32 PM) *
A really good colorist (did I just make that up?)


No, you didn't make it up. Colorists have a rich history, going back to those who colored the black and white wood and copper engravings in early printed maps. Antique maps with "original color" are much sought after. Antique black and white maps that have had color added in recent decades are frowned upon.

I'm glad that we can have both grayscale and color versions here on UMSF.
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brellis
post Dec 31 2009, 03:36 AM
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Color pics are really just a relatively narrow band of spectrograph, nest-ce pas?
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tedstryk
post Dec 31 2009, 04:49 AM
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Very true.


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ugordan
post Dec 31 2009, 11:59 AM
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QUOTE (brellis @ Dec 31 2009, 04:36 AM) *
Color pics are really just a relatively narrow band of spectrograph, nest-ce pas?


Not color pics per se, but human eye can see only in some 300 nm wavelength span. Space rocks generally have flat spectra and the curves are not very steep (generally pick your favorite shade of red/brown), providing for very soft hues. If your color pics are composed of say UV and IR filters (in addition to one filter covering the visible - typically green), extending beyond the visible, they are called "enhanced color" in that they effectively increase saturation on abovementioned objects with flat spectra.


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ugordan
post Jan 1 2010, 09:19 PM
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Here are a few color pics I've been working on. Chronologically, first an MRI inbound view showing a subtle shadow the nucleus is casting on its coma (looks better without the white webpage background):



Three views of the impact:


Finally, and probably my favorite is the look-back view, both MRI and HRI imagers:







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