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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Sep 14 2005, 07:03 PM
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#2
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Founder Group: Chairman Posts: 14448 Joined: 8-February 04 Member No.: 1 |
I'm guessing there's no flatfield or darkfield for the Surveyor stuff ( where can you get it all anyway?)
If you took all the surveyor frames that didnt include the 'sky' and averaged them, you might get an appropriate 'flat field' - which you could then invert, and overlay at a few percent opacity on all the other frames. Doug |
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Sep 14 2005, 07:32 PM
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#3
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Interplanetary Dumpster Diver Group: Admin Posts: 4405 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
I usually try to make a blank image with my digital camera to record only the vignetting so that it can be subtracted. Here are some pans where it works well. Sometimes it works, sometimes it doesn't. To do this automatically would be great!
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