1. A method of reducing noise in a sequence of digital video frames, comprising the steps of: estimating motion between a current noisy frame and a previous noise-reduced frame, to generate motion vectors indicating relative motion between the pixels in the current noisy frame and the corresponding pixels in the previous noise-reduced frame; and removing noise from the current noisy frame by computing the weighted average of pixels in the current noise frame and said corresponding pixels in the previous noise-reduced frame based on the motion vectors, to generate a noise-reduced output frame.