Ever notice? Sometimes when you’re watching a movie on the big screen, a bright green oval will momentarily appear somewhere in the picture. It never lasts very long – maybe the duration of one or three frames. Always an oval, always green. What is that? What causes it? Presumably it has something to do with the chemical composition of celluloid.
And sometimes you see a vertical line running through the whole picture – also green – which can last a lot longer.