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Manipulating Phoenix RDR images, They're 32 bit -- how do I deal with that?
elakdawalla
post Mar 24 2009, 01:03 AM
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In anticipation of writing about the "droplets on the legs" story I wanted to go play with the calibrated RAC images of Holy Cow. But the RDRs are 32-bit images, and I'm not sure how to open them. NASAView can at least open and display them, but it applies an automatic contrast stretch (I think) and only permits output as 8-bit GIFs or JPEGs. In an ideal world I'd like to be able to convert them all to 16-bit images in any format that Photoshop can read, using a common conversion from 32 to 16 bits -- does anybody have any advice?

Here is a sample image (the first, from sol 5). Text header is at the beginning of the file. I would be quite happy to track down and provide all the .IMG files for the Holy Cow images that have been released to date to anyone who wants to play with them.

--Emily


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ugordan
post Mar 24 2009, 05:20 PM
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How many images do you need converted? If it's not too many I could do it manually, rather than releasing this 15-minute hack job of QUB2PNG I just did. Here's the sample 16 bit PNG:

Attached Image


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elakdawalla
post Mar 24 2009, 05:35 PM
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I found 19 images of spotty struts in the PDS, but the money shots seem to be these three:

rs008rad896930338_11856mdr1
rs031rad898970546_13820mdr1
rs044rad900125912_14de0mdr1

Thanks for your help. I think I could probably use GIMP to do this but I really need to learn how to use GIMP to manipulate 8- and 16-bit images (which I haven't done yet) before I start mucking about with 32-bit ones.

--Emily


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ugordan
post Mar 24 2009, 05:41 PM
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Here they are. Note the calibrated output uses physical units (I *think*) so it's impossible for me to find a scaling factor that stretches saturated pixels to white. These are scaled the same amount as the one above.

Attached Image

Attached Image

Attached Image


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elakdawalla
post Mar 24 2009, 05:48 PM
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Lovely, thank you, I feel much better about staring at these pixels than I do with the NASAView -> GIF versions.

In the end though I just don't know what to make of the images. The Renno abstract uses the phrase "smoking gun" three times. I don't see anything wrong with his arguments but I just don't feel comfortable agreeing with the statement "we see liquids on Mars right now!" based upon images of "drops" that are only a few pixels across. Guess they're the experts though.

--Emily


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siravan
post Mar 25 2009, 02:27 AM
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I just wrote a small utility file to convert 32 bits IMG files to 16 bits FITS format. I cannot upload it to the forum (it is an EXE file), but I can email it (or the C code) to anyone who is interested.[attachment=17662:test.png][attachment=17662:test.png]
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