OK, I was actually referring to color correction on an UW video (which actually contained a greenish sand area around my light-illuminated subject.
Editors of UW video spend a lot of time fighting the "greenies". Viewers expect UW footage to be blue.
Two options:
1. we could take a united stand and insist "no, sometimes it is green - get used to it", or
2. we can fix it.
The hardest to fix is when you have a foreground subject that's lit by lights (subject is already the right color), and a background that's vomit green. Even worse when the subject is say a gorgonian fan coral and you can see bits of the green background through the fan coral. I had such a case in a video that I'm editing at the moment: a promo video for a dive boat operator.
Took about 30 minutes of playing around with the 3-way color corrector and its "limiter" twirl down to get all the color to where it was OK, with the gorgonian still deep red and the background more bluish than green. The important factor was adjusting the sensitivity (the width of the bottom of the trapezoid) of the limiter for both luma and color. Too tight and the background started shimmering. Too loose and the gorgonian started to change color.
Two things worth remembering:
1. You can add multiple color corrector filter to one clip. if you are subtle in the adjustments, you can fix one problem in on filter (e.g. the overall contrast or a color cast) and anothet problem with a second filter (e.g. a green background).
2. You can key the filters so that effect of the filter change over time (e.g. a color issue that occurs in only one part of a longer clip or one that progessively changes throughout a clip). Fiddly but doable.
For UW video editors, well worth spending some time mastering this tool.
Regards
Peter