Reprocessing Historical Images, Looking for REALLY big challenges? |
Reprocessing Historical Images, Looking for REALLY big challenges? |
Apr 21 2005, 11:26 PM
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Member Group: Members Posts: 123 Joined: 21-February 05 Member No.: 175 |
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Apr 24 2005, 09:39 AM
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
One annoying problem with the radiometrically corrected Mariner 69 images was a "cleanup" that was only partially done. The camera had electrical interference that made noticible periodic noise "herringbone", etc. patterns in the data. This was removed from the full resolution analog data by Fourier transformation of the data, isolation of the noise frequencies in 2-D frequency space, and transformation back into Cartesian image space.
This was ***NOT*** trivial in 1970. Unfortunately, the same noise pattern was present in the 1/7 and the 1/28 digital data streams, aliased by the 1/7 and 1/28 undersampling of the data. You can see it in the pictures posted above. Unfortunately, they did not remove the periodic noise from the digital data streams, and that was put back into the images when the digital data was merged with the analog data. The radiometrically restored images thus had the periodic noise from the 1/7 data in the outer parts of the image, and the different pattern of noise from the 1/28 data in the middle strip. *SIGH*. Easy enough to fix now, just very "fiddly" work. I really do want to see what color information we can get out of the Mariner 6 and 7 pics. I've wanted that for 35 years. |
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Apr 27 2005, 01:55 AM
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Member Group: Members Posts: 123 Joined: 21-February 05 Member No.: 175 |
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