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Old 25-09-2013, 05:33 PM
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irwjager (Ivo)
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Join Date: Apr 2010
Location: Melbourne
Posts: 532
Quote:
Originally Posted by multiweb View Post
So you debayer filtered to LUM, unfiltered to RGB, extract the LUM and do LUM1 - LUM2 and that's your bias that you can subtract into the color?
Just to be clear, with an OSC or DSLR;

1. Acquire without filter, debayer as normal, call this your RGB.
2. Acquire with filter, debayer as normal, call this your L
3. Convert L to grayscale (*average* the channels, don't use lightness, luminance, etc. - you'll want to weigh each channel the same, i.e. 33.3%), now you got your L, ready to go.
4. Create a model of the light pollution that exists in your unfiltered RGB image (keep your RGB linear!), call this M.
5. Put RGB in a layer, put M on top, set M's layer to 'subtract'.
6. Save the 'RGB-M' result as your new RGB; RGB without light pollution.
7. Process and combine L and light pollution-free RGB with your favorite method.

Happy to give anyone a hand if you got the data!
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