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Algorithm that removes the water from underwater images

Started Nov 13, 2019 | Discussions thread
PHXAZCRAIG
PHXAZCRAIG Forum Pro • Posts: 19,651
Re: Algorithm that removes the water from underwater images

I like the idea, which seems aimed for accuracy as much as anything.   But also in shallow water perhaps, where there is still a range of colors to be had.

What it looks like to me is that a) the white balance is correct, and b) a lot of haze has been removed by increasing the contrast.  (Note how much darker it seems after correction.)

What I've found in my own post-processing is that the first thing you try to do is get the white balance right.  And I go back and touch it up a fair amount sometimes before I am happy with the result.  It would be nice to know right off what white balance settings to try.    That gets colors right and fixes a host of woes, but it doesn't help haze in the water.

If you look at a histogram of a hazy scene, it usually is very narrow with low contrast.  A lot of adjustments will take the bright side of a histogram right to the limits, but leave a hazy 'whitish' look.  And the histogram of the scene will often have little or nothing near the dark edge.  At that point pulling the black point slider down a bit will stretch the left (dark) side of the histogram to increase contrast - and often makes the haze disappear.

But it's all done by eye, with countering adjustments often needed.

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Phoenix Arizona Craig
www.cjcphoto.net
"In theory, practice and theory are the same. In practice, they're not."

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