Vignetting, discussion about methods of resolution |
Vignetting, discussion about methods of resolution |
Aug 24 2005, 07:37 AM
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#1
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Member Group: Members Posts: 877 Joined: 7-March 05 From: Switzerland Member No.: 186 |
Hi Nirgal and all, I would like to discuss about vignetting and methods of resolution for it. I'm mainly interested in mathematical methods that could automatically calculate and adjust the right grey value for each pixel in a single picture.
My current method works with more or less transparent layers over the original picture that so roughly are able to balance the grey values. A perfect layer have to be the exact inverted brightness difference of each picture with this shadow effects. This method is very effective if you get the correct inverted values. These shots of the Mars sky come nearly at such a perfect mask, but not always. And of course the center of the pictures lose much of theirs original brightness/luminance sadly. I have in mind a mathematical method that can adjust each grey value in a pic in order to obtain a completely balanced brightness over the entire picture. But I'm not in the position to reach that. I only know one have to start with the calculation of the grey values in the center of the picture. In the center are quasi the reference values of the whole picture, if I'm correct. Is there a possibility (mathematical method) to get (roughly) the same brightness and luminance like in the center over the whole picture from the MERs? Greetings, Peter -------------------- |
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Jul 10 2006, 06:19 AM
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#2
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Junior Member Group: Members Posts: 37 Joined: 20-November 05 Member No.: 561 |
I would like to point out that the program um3k's first link above:
http://pds-rings.seti.org/catalog/vgriss.html is the program for getting rid of reseau and for correcting the geometric distortion. I've played with it a few days and it works fine even in my little Libretto computer. It has special settings for Voyager or Viking orbiter images, and seems to have almost as many complicated controls as Photoshop! (I imagine.) The only thing is that it doesn't automatically do the flat-fielding--special flat-field images must be loaded into it. But is has separate settings for "flat-field" and "dark current"--didn't even know there was a difference. |
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