Video noise reduction

Noise reduction analyses a frame, and usually the frames around it, to separate random sensor grain from real detail. Temporal methods compare across time and hold detail better; spatial methods work within a single frame and are faster. Push either too far and skin turns to plastic, hair smears, and fine texture in fabric disappears. Rendering it is slow too. Most editors apply it only to the shots that need it, and getting exposure right in camera is worth more than any cleanup afterwards, since noise reduction can only remove information rather than restore it.