Processed Cassini Jupiter Images, Fun with the PDS files |
Processed Cassini Jupiter Images, Fun with the PDS files |
Aug 3 2005, 10:26 PM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Now that I have downloaded all of the PDS formatted Cassini Jupiter images (and actually all of the Saturn images too) I have been experimenting with processing calibrated versions of them:
http://www.mmedia.is/bjj/misc/css_stuff/im...grnbl1_proc.jpg http://www.mmedia.is/bjj/misc/css_stuff/im...olor_mosaic.jpg The first one is simply a global view composed from CB1 (red), GRN and BL1 filtered images with the color balance adjusted to make it more realistic and with some sharpening applied to the image. This is a preliminary version, it looks very bluish at the limb due to Jupiter's rotation (I preferred this to color fringing at the center of Jupiter's disk). Later I plan to fix this by rotating the images in 3D space. The second one is a reprocessed version of the well known Io transit image but with the addition of the north polar region - since this is a preliminary version some seams may be visible. Later this may turn into a global mosaic. The color balance is also improved. The 'official' image seems to have been composed from CB2, (CB2+BL1)/2 and BL1 filtered images (only CB2 and BL1 images are available). Using CB2 as red makes the belts too reddish if you want whitish zones. To fix this I used a synthetic CB1 image created from a linear combination of the CB2 and BL1 images. Needless to say I also used a synthetic green image. Now the plan is to do a big cylindrical map of Jupiter followed by an even bigger one of Saturn. |
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Jul 10 2012, 02:20 PM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
This is a 2x2 mosaic of Cassini images obtained on November 30, 2000 from a distance of 30 million km:
The majority of global images of Jupiter includes the Great Red Spot (GRS) and in most of these the GRS is near the center of the disc or a bit towards the terminator. This one is an exception and shows the GRS near the limb. CB2 (near infrared) and BL1 (blue) images were used. At this time Cassini wasn't taking green filtered images so I created a synthetic green image as GRN = 1.126959 x (0.481 x CB2 + 0.519 x BL1). I also created a synthetic red (CB1) image as CB1 = 1.106251 x (0.774 x CB2 + 0.226 x BL1) using CB1, GRN and BL1 images obtained at a greater range a few weeks earlier as a guide. I then altered the color balance slightly to make the bright zones more whitish and less yellowish (actually the real color of the zones might be slightly yellowish so in retrospect maybe I should have omitted this processing step). The images were reprojected to simple cylindrical projection, mosaiced and then rendered using the viewing geometry Cassini had when it took one of the BL1 images. The final step was to sharpen the resulting image slightly. |
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