Method and apparatus for controlling loop filtering or post filtering in block based motion compensationed video coding

An encoder for encoding an image, comprising:

• a processor adapted to:
• compare blocks in a same image frame with reference frames;
• transform a result of the comparison between the reference frames and the blocks in the image frame into transformed blocks having transform coefficients;
• compare are the similarities between the transform coefficients for spatially adjacent transformed blocks within the same image frame;
• and
• skipping deblock filtering between spatially adjacent transformed blocks in the image that have the same or similar transform coefficients.

A decoder for decoding an encoded image, comprising:

• a processor adapted to identify spatially adjacent blocks in the encoded image;
• identify coding parameters including D.C. coefficients for the spatially adjacent blocks within a same encoded image frame;
• compare the identified D.C. coefficients between the identified spatially adjacent blocks;
• and
• enable or disable filtering of blocking artifacts between the spatially adjacent blocks according to the comparison of the D.C. coefficients between the spatially adjacent blocks within the same encoded image frame.

An image decoding method, comprising:

• storing reference images for an image to be decoded, the stored reference images being for motion compensation prediction of the image to be decoded;
• obtaining a reference block from the stored reference images according to a motion vector;
• inverse quantizing and inverse transforming an output of a variable length decoder to obtain a decoded difference block;
• decoding an image from the reference block and the decoded difference block;
• generating a reconstructed image based on the decoding;
• and
• judging whether or not to execute deblock filtering for each boundary between adjacent blocks in the reconstructed image with respect to each of a luminance channel and a chrominance channel for the adjacent blocks, wherein
• the judging includes determining, with respect to one of the luminance channel or the chrominance channel for the adjacent blocks, whether or not motion vectors of the adjacent blocks are equal to each other as well as whether or not the motion vectors of the adjacent blocks point to the same reference image, and
• in response to determining that the motion vectors of the adjacent blocks are not equal to each other and do not point to the same reference image, executing deblock filtering for a boundary of the adjacent blocks in the reconstructed image corresponding to the luminance channel and a boundary of the adjacent blocks in the reconstructed image corresponding to the chrominance channel.