How to process occultation images?

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Francisco Mello avatar
Hello everyone. Im new to the forum space and I would like to ask a question. Yesterday (08/20) there was a lunar occultion with Saturn and the Moon. And i would like to know how I can process it so the Moon doesn't appear very bright and Saturn doesn't appear to dim. Thanks
Tony Gondola avatar
I would make separate properly exposed stacks for the moon and Saturn and then composite them together in Photoshop, Gimp, Affinity Photo, whatever you are using. I even had to do that for the Jupiter/Saturn conjunction a few years back because the difference between the two was just to much to get the image I wanted.
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Francisco Mello avatar
Thanks for the help! I think i will do that, i really cant find another solution than making a composite
andrea tasselli avatar
If no area is overexposed (as the Moon crossing would have been in the Moon's shadow if I recall right) or underexposed then it is possible to modulate the relative brightness using a non-linear transformation. To be more specific we would need to have an example and what are you using to create the final image (a movie, a single shot, a collection of single shots etc).
Victor Van Puyenbroeck avatar
I searched for an exposure time and gain that would not blow out the Lunar surface, but still show Saturn. The stacked image below was treated with non-linear curves (like Andrea said) to improve visibility of the planet while keeping the lunar surface under control. In my opinion, you can get a more pleasing image by making a composite. It gives you the best contrast in each object.
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Francisco Mello avatar
andrea tasselli:
If no area is overexposed (as the Moon crossing would have been in the Moon's shadow if I recall right) or underexposed then it is possible to modulate the relative brightness using a non-linear transformation. To be more specific we would need to have an example and what are you using to create the final image (a movie, a single shot, a collection of single shots etc).

I made a movie of the entire occultation process, after that I stacked the first 800 frames of the film.
Francisco Mello avatar
Victor Van Puyenbroeck:
I searched for an exposure time and gain that would not blow out the Lunar surface, but still show Saturn. The stacked image below was treated with non-linear curves (like Andrea said) to improve visibility of the planet while keeping the lunar surface under control. In my opinion, you can get a more pleasing image by making a composite. It gives you the best contrast in each object.

Totally. I did get a quite pleasing result but a composite is still a better choice
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