I was working on an animation in After Effects and noticed that after I had applied a blur vignette (i.e., put fast blur over a layer, and put a circular mask over the top, like a vignette but blurred on the edges) and noticed that the edges started to ripple. Below is an example image. I was just wondering what caused this. Thanks in advance!
What you are experiencing in more commonly known as banding. There are a few things you can do to try and eliminate that:
Work @ 32 bit color space- this will allow for smooth blurs and gradients. However that will change the way some plugins interact with the elements (some are not even built for 32bit) and change the final look.
Add noise/grain on the blur- this will minimize banding.