> noise (which does not compress according to information theory) That's true in theory/isolation, but in practice we know the noise has much lower maximum amp

> noise (which does not compress according to information theory) That's true in theory/isolation, but in practice we know the noise has much lower maximum amplitude than the original image. I.e. if you take a difference between two frames, almost all of it will require less bits per pixel than the signal. (And that allows compression in practice)