Recursive noise reducer

Abstract

A noise reducer to which image data (Y IN) obtained by decoding coding data using a DCT coding is supplied. The noise reducer is comprised as follows. Noise extracting unit (26, 29) for extracting a noise component, first and second noise cancelling unit for cancelling the extracted noise component from input image data, a memory (28) for delaying the image data from the first noise cancelling unit (27) by a predetermined amount and supplying the delayed image data to the noise extracting unit, decimating unit for decimating the image data to be written into the memory, and interpolating unit (30) for interpolating an output of the noise extracting unit and supplying the interpolated output to the second noise cancelling unit (24, 25) whose output is taken out.

Description

technical field [0001] The present invention relates to a recursive noise reducer which is particularly suitable when applied, for example, to the decoding of image signals encoded using DCT. Background technique [0002] Recursive noise reducers using a frame memory are known in the field of digital image signal processing. The noise reducer is constructed in such a manner that part of a small level in a difference between an input image signal and a video signal of the previous frame from the frame memory is processed as a noise. The extracted noise component is extracted and subtracted from the input image signal such that the noise is reduced and the signal in which the noise is reduced is written into the frame memory. If a field memory is used instead of the frame memory, the capacity of the memory can be reduced. [0003] DCT (Discrete Cosine Transform) is used in image compression encoding of the MPEG (Moving Picture Experts Group) standard and the like. This DCT ...

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Problems solved by technology

However, the block distortion cannot be predicted correctly according to the state of an image and there is a possibility of erroneous operation

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