Deep Impact camera data, Messing about with images from the PDS Options

[elakdawalla]

I'm wondering if anybody here has spent any time working on the Tempel 1 images from Deep Impact. The data are available at the Small Bodies Node (see e.g. http://pdssbn.astro.umd.edu/holdings/dif-c...0/dataset.html), and Version 2 of the PDS archive (which appears to have been published 3 years ago) includes versions of the data that have been calibrated, cleaned of instrument artifacts, and converted to units of radiance and also I/F. The HRI data have not been deconvolved to remove the blur: a bit of playing shows that without deconvolution, HRI images look pretty similar to MRI images. Attached is a color composite I made of the highest-resolution full-globe shots of Tempel 1 captured by the MRI before the impact. The image isn't big but there's more variety in color than I expected. This is made from the I/F images and is an RGB composite of red, green, and violet continuum filter images, overlaid over a clear image that I sharpened slightly. It's very red, but I think that's real.

Has anybody else worked with these?

Attached thumbnail(s)

 

[elakdawalla]

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.

[tedstryk]

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.

[ugordan]

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.

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.

[tedstryk]

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.

[ElkGroveDan]

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.