Brownian motion refers to the random motion of particles in a fluid, resulting from their collision with fast-moving particles in the fluid. And a fluid, of course, could be a liquid or a gas.
But, if photographic outcomes were subject to Brownian motion, then it would be a crap-shoot every time we took a picture.
To explain something like this:
as being due to Brownian motion is really, really stupid.
In film photography, there is a motion particles: silver particles. But, it isn't Brownian motion, which is random. It's motion in response to light. It's photo-sensitive motion. The silver particles move and aggregate in response to their being exposed to light. It's not Brownian motion. It's not a random motion.
If Brownian motion was moving the silver particles, then we would NEVER get accurate and reliable photographic images. Randomness. You understand what it means, right, Professor Norwood? If the silver particles were moving randomly due to Brownian motion, then they would move randomly all the time, and we would never get decent pictures.