Method and apparatus for encoding and decoding image using adaptive interpolation filter

An image encoding apparatus comprising:

• a motion predictor which generates a motion vector of a current block to be encoded by performing motion prediction of the current block using fractional pixel resolution;
• an interpolation filter generator which generates an interpolation filter for interpolating fractional pixels between integer pixels in an adjacent area of a reference picture according to fractional pixel resolution of the motion vector of the current block using the adjacent area of the reference picture corresponding to an adjacent area of the current block, the adjacent area of the current block having been encoded and decoded, the interpolation filter interpolating the adjacent area of the reference picture to minimize a difference between an interpolated adjacent area of the reference picture and a corresponding adjacent area of the current block;
• and
• an interpolator which interpolates a corresponding block of the current block, which is indicated by the motion vector having the fractional pixel resolution, using the generated interpolation filter.

An image decoding method comprising:

• extracting motion vector information of a current block to be decoded from a received bitstream;
• if the extracted motion vector of the current block is a motion block having fractional pixel resolution, determining an adjacent area of a reference picture corresponding to an adjacent area of the current block, the adjacent area of the current block having been decoded;
• generating an interpolation filter for interpolating fractional pixels between integer pixels in the adjacent area of the reference picture according to the fractional pixel resolution of the motion vector of the current block, the interpolation filter interpolating the adjacent area of the reference picture to minimize a difference between the interpolated adjacent area of the reference picture and a corresponding adjacent area of the current block;
• and
• interpolating a corresponding block of the current block, which is indicated by the motion vector having the fractional pixel resolution, using the generated interpolation filter.

An image decoding apparatus comprising:

• a motion vector extractor which extracts motion vector information of a current block to be decoded from a received bitstream;
• an interpolation filter generator which generates, if the extracted motion vector of the current block is a motion block having fractional pixel resolution, an interpolation filter for interpolating fractional pixels between integer pixels in an adjacent area of a reference picture according to the fractional pixel resolution of the motion vector of the current block using the adjacent area of the reference picture corresponding to an adjacent area of the current block, the adjacent area of the current block having been decoded, the interpolation filter interpolating the adjacent area of the reference picture to minimize a difference between an interpolated adjacent area of the reference picture and a corresponding adjacent area of the current block;
• and
• an interpolator which interpolates a corresponding block of the current block, which is indicated by the motion vector having the fractional pixel resolution, using the generated interpolation filter.