Abstract: Provided are a method and apparatus for encoding an image capable of improving compression efficiency of the image by compensating for a loss due to quantization of a residual block in the frequency domain, and a method and apparatus for decoding the image. The method of encoding an image includes: generating a prediction macro block for a current macro block; generating a first residual block which is a difference between the prediction macro block and the current macro block; generating a compensation residual block by compensating for a quantization loss of the first residual block in the frequency domain; compensating for the prediction macro block by adding the compensation residual block and the prediction macro block.

Abstract: A method of and apparatus for encoding and decoding an image are provided. According to the method and apparatus, a virtual motion vector is assigned to a block which is encoded in intra prediction mode, and when a motion vector of a block which is encoded in inter prediction mode after the intra block is decoded, the virtual motion vector assigned to the intra block is used.

Abstract: Provided are a method and apparatus for encoding an image capable of improving compression efficiency of the image by compensating for a loss due to quantization of a residual block in the frequency domain, and a method and apparatus for decoding the image. The method of encoding an image includes: generating a prediction macro block for a current macro block; generating a first residual block which is a difference between the prediction macro block and the current macro block; generating a compensation residual block by compensating for a quantization loss of the first residual block in the frequency domain; compensating for the prediction macro block by adding the compensation residual block and the prediction macro block.

Abstract: Provided are methods and apparatuses for encoding an image and methods and apparatuses for decoding an image. The methods and apparatuses generate a compensated prediction block by compensating a prediction block of a current block by using a predetermined compensation value and encode a residual value that is a difference between the compensated prediction block and an input current block.

Abstract: Methods of coding a bitstream in which the frames are encoded for enabling a spatial resolution is changed in real time, extracting the bitstream by adding a signaling message indicating that the spatial resolution is changed, and decoding the bitstream in which the spatial resolution is changed in real time after actively detects whether the spatial resolution is changed without additional information, and a codec using the methods are provided. Therefore, if the network has the restricted environment that the resolution is changed in real time while a video encoding and decoding or if there is a need to output the video whose the spatial resolution is partly changed in the decoder, the present invention provides methods to actively cope with the spatial resolution change of the video so as to efficiently watch the video.

Abstract: A method of and apparatus for encoding and decoding an image are provided. According to the method and apparatus, a virtual motion vector is assigned to a block which is encoded in intra prediction mode, and when a motion vector of a block which is encoded in inter prediction mode after the intra block is decoded, the virtual motion vector assigned to the intra block is used.

Abstract: Provided are a method and apparatus for video predictive encoding and decoding, in which a prediction value of a current block is generated by using a motion vector, which is generated by motion estimation with respect to a neighboring area located adjacent to the current block, as a motion vector for the current block. The motion vector to be used for motion compensation with respect to the current block can be determined by motion estimation using a previously processed neighboring area without separate transmission of motion vector information regarding the current block, thereby reducing the amount of bits generated during encoding.