Frames of a digital video signal are spatially filtered to remove impulse
and other noise from the video signal. The spatially filtered frame is
temporally filtered to further remove noise from the digital video signal.
The spatial filter is adaptive, heavily filtering portions of low detail
in the represented subject matter while lightly filtering or not filtering
portions of moderate to high detail in the represented subject matter. As
a result, clarity and detail in the subject matter of the digital video
signal are preserved. The temporal filter is similarly adaptive and
determines if and to what degree the subject matter of portions of the
spatially filtered frame correlate with corresponding portions of a
previous frame. By previously spatially filtering the frame,
determinations regarding the correlation of the current frame with
corresponding portions of the previous, which is also spatially and
temporally filtered, are more accurate. Accordingly, temporal filtering
can be performed more aggressively without temporally blurring the digital
video signal. The result of spatial and temporal filtering of the digital
video signal is significant reduction in noise without degradation of the
signal and improved compression of the digital video signal.