04-06-2023, 07:38 PM
(04-06-2023, 11:49 AM)Stuart Wrote: It's more to do with skin tone contrasts. Nobody is actually green, even when a bit poorly.
That doesn't explain why it was changed, of course.
I've had a look around to see if there were any posts on TV Forum, or from elsewhere, and I've come up with this from noggin on TV Forum:
noggin from TV Forum Wrote:Of course now we have 4:2:2 to cope with, we no longer have full-bandwith RGB, which is why Green-screen is a much better choice than blue-screen for a high quality video key these days (as you get much more G content in the full-bandwith Y channel than you do B content, which is mainly carried in a half-bandwith Cb channel)
And I also found this:
noggin from TV Forum Wrote:In current 3CCD studio cameras that isn't the case, as they use three separate sensors of equal resolution. Ikegami made an SD 4 CCD camera with two offset green sensors to increase the green resolution - but there were also issues about avoiding the EU's 3CCD import tariffs ISTR (a 4CCD camera didn't count?)
However the 4:2:2 YCrCb sampling system used to get pictures from camera CCUs into vision mixers does favour green over red and blue.
Single-sensor cameras used for location filming (and high-end 4K OBs like the Sony F55) use a single large sensor (similar to DSLRs) that use a Beyer or similar filter pattern that usually has twice as many green sensor sites as Red and Blue (often a 2x2 block with 2 Green, 1 Red and 1 Blue)
Which suggests it was a consideration in the early days of digital studio cameras, but hasn't been for a while.