Quote Originally Posted by Michael Fanelli
Root Mean Square is a "fancy average." For a sine wave, such as the current that comes out of an AC outlet, it is 0.707 of the peak amplitude. For film grain, its basically the same thing for "peak size of the grain." It makes sure that plus and minus values don't cancel each other out. Lower is better.

lol, that would have been my answer too I took electronics... not photography!

JS