eli5 why there is noise in pictures taken in the dark?

Question

I was always wondering about this because I don’t understand why I can see random colorful pixels when shooting something in the dark…why is that?

In: 3

Answer 1

Cameras aren’t very sensitive in the dark. The picture you get would ordinarily be very very dark, but the brightness is amplified to get something more viewable. Unfortunately, due to the camera’s insensitivity in the dark, this reveals a lot of noise.

You don’t see that noise in daytime photos because there’s so much light coming into the camera, you don’t need to rely on amplifying the bare minimum that the imagine sensor can handle. The noise is entirely drowned out by the good image signal.