Galileo images and mosaics of Europa |
Galileo images and mosaics of Europa |
Aug 22 2005, 04:03 AM
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#1
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
I have worked on sprucing up some global views of Europa from Galileo. There are a few more global views I hope to get to eventually. But the best two at nearly full phase benefited a lot.
[Moderator note: There are several more threads containing Galileo Europa images but they all contain several inactive image links. The main threads are: http://www.unmannedspaceflight.com/index.php?showtopic=2016 http://www.unmannedspaceflight.com/index.php?showtopic=2174 http://www.unmannedspaceflight.com/index.php?showtopic=2222 http://www.unmannedspaceflight.com/index.php?showtopic=2082 http://www.unmannedspaceflight.com/index.php?showtopic=2142 ] -------------------- |
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Aug 23 2005, 12:50 PM
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#2
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
If you consider the Galileo filters and their wavelenghts, you have:
Violet - 404 : Green - 559 : Red - 671 : IR756 - 756 : IR968 - 968 The human color vision has a peak response of: Blue - 440 : Green - 510 : Red - 650 So to "convert" the Galileo filters in to "human colors" we can mix images from different filters to get the proper wavelenghts. I've calculated the ratios and corresponding wavelenghts: 75% Violet + 25% Green = blue (443) 70% Green + 30% Violet = green (513) 80% Red + 20% Green = red (649) 50% IR756 + 50% Green = red (658) 20% IR968 + 80% Green = red (641) I've tried this on two Europa images and the results look good. Saturation is low, but that's expected when you mix the color data. Also, Europa looks white through a telescope anyway ;-) -------------------- _______________________
www.astrosurf.com/nunes |
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Aug 23 2005, 03:45 PM
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#3
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
I experimented with filter mixes. Realistically, the problem is that Galileo image quality varies wildly depending on compression used. Also, it is rare to get a color mosaic without some bad gaps. But I did use similar mixes.
Bjorn: I see the problem in my large mosaic, but could you point out what you are talking about in my other images? I am not sure which spots you are referring to, and would like to know so I can try to correct the problem. Some of what you are seeing may be due to the fact that I jacked the contrast up on the posted images. -------------------- |
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Aug 23 2005, 04:25 PM
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#4
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
The pinkish areas are very prominent in the C10 image (the message dated yesterday at 05:29 PM), especially in the bright areas near the left limb and near Pwyll.
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