Thread: Diving video
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Old 10th June 2018, 05:24   #60  |  Link
WorBry
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Quote:
Originally Posted by shekh View Post
@Bryan: It may be good idea but it will definitely blow up the filter (more complex math and UI). So maybe another one. Never had success yet with shadow-highlight separation, maybe it is too subtle for me
T'was just a thought. Maybe could be applied through masked overlays, but that's not something I've really explored in Vdub. There's RGB (gradation) curves also, of course -not for the faint hearted.

Quote:
Originally Posted by shekh View Post
Interesting that you applied channel mixer, I supposed that red-green and yellow-blue sliders achieve the same
Yes, with that first 'green-cast' sample (Test#1), using the '6-axis' filter alone I can get pretty close to the color balance obtained with Channel Mixer + tweaked with '6-axis'. But with the 'blue-cast' clip with the blanked red channel that Tormento provided, no, at least not to end up with an orange finned fish It was the same in Resolve - pushing the color wheels to the extreme was not enough - always fighting an offset cast; the red channel needed reconstructing.

Also I wanted to see how well I could replicate the Resolve workflow using VDub.

Quote:
Originally Posted by shekh View Post
Also levels... is exactly the purpose of top slider (intensity). Have you tried?
I didn't in those examples, but I have now. Sometimes I just use curves when manipulating levels and contrast (S-curve) at the same time.

Quote:
Originally Posted by shekh View Post
I'll try to pick some decent shots for experiments, if you want.
Thanks, it would be interesting to test some good quality, native clips with strong casts/blanked red channels, ideally including sea life with known (and unambiguous) color characteristics, to see how well these methods hold-up.

Actually I just figured out an easier way to do the channel 'reconstruction' (redistribution) using what Resolve calls a 'Splitter-Combiner' node - basically splits the input into monochrome R,G, B channels with a separate node for each, so you can work on them independently, and combines them again. What I've done is to create blend (composite) overlays (layer nodes) between the monochrome G and R nodes and G and B nodes, with the G feed as the top layer and 'Add' as the blend mode. In that way, the redistribution of G channel luminance can be controlled by balancing the opacities (key gain in Resolve) of the two layer nodes. Fine tuning is then largely a matter of adjusting Color Temperature/Tint. Works very nicely and much easier than nudging individual sub-channel values.

Thinking about what I said earlier:

Quote:
Originally Posted by WorBry View Post
I could be wrong, but I think the chances of coming up with an AVS plugin for 'automated' underwater color correction are pretty remote. Closest I could imagine would be a Channel Mixer based function that maybe has generic presets for depleted channel reconstruction when there is blue or green bias, which can then be tweaked.
That's something that could applied in AVISynth (I think) - a Channel Mixer function (with sub-aqua absorption biases in mind) controlled via layer blend opacities.

Quote:
Originally Posted by shekh View Post
@StainlessS: It honestly looks in real water like the unprocessed from camera.
It's been many years since I last went diving (mostly Red Sea and Persian Gulf), but that unprocessed sample with the strong green cast (Test#1) is really how it would have looked to the diver? Maybe I never went deep enough. Is that where the phrase 'looking at the world through rose colored goggles' comes from ?
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Last edited by WorBry; 10th June 2018 at 07:18.
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