Method and apparatus for encoding/decoding video using adaptive filtering

PURPOSE: An image encoding method and a device thereof, a decoding method and the device thereof using adaptive filtering are provided to perform prediction encoding based on a filtered reference frame and transmit a part of information of an applied filter, thereby increasing compression efficiency of an image. CONSTITUTION: A filtering unit(120) determines a filter applied for a reference frame and filters the reference frame through the determined filter by changing a size of the filter applied for the reference frame used for prediction encoding of an encoded current block and a filter coefficient of the filter. A prediction encoding unit(110) encodes the current block by using the reference frame. An outputting unit(130) outputs information about predictive encoded data of the current block and the filter. [Reference numerals] (110) Prediction encoding unit; (120) Filtering unit; (130) Outputting unit; (AA) Input image