Patent ID: 8218083
Filing Date: 2012-07-10
Classification: H04N

Abstract:
1. A noise reducer of the three-dimensional type for reducing noise components lacking frame-to-frame correlation in a video signal representing values of pixels, the noise reducer comprising: a subtractor for receiving the video signal of a current frame and the video signal of a preceding frame or a noise-reduced video signal output from the noise reducer in the preceding frame, taking a difference between the video signal of the current frame and the video signal of the preceding frame, or a difference between the video signal of the current frame and the noise-reduced signal output from the noise reducer in the preceding frame, and outputting the difference as a frame difference signal; a motion detector for processing the frame difference signal to detect motion in the video signal and derive a motion detection signal indicating a motion level for each pixel; a noise decision unit responsive to the frame difference signal for extracting a high-frequency component of the frame difference signal for each pixel, processing the high-frequency component to detect noise in the video signal, and outputting a noise detection signal indicating a noise level for each pixel; a motion level calculator for deriving a motion level signal for each pixel from the motion detection signal and the noise detection signal by a process that includes at least taking a difference between the motion detection signal and the noise detection signal; a coefficient calculation unit for converting the motion level signal to a recursion coefficient; a multiplier for multiplying the frame difference by the recursion coefficient to obtain a noise recursion quantity; and an adder for additively combining the noise recursion quantity and the video signal of the current frame to obtain a noise-reduced video signal for the current frame and outputting the noise-reduced video signal.