Method for determining filter coefficient of two-dimensional adaptive interpolation filter

An apparatus which determines a filter coefficient of a two-dimensional adaptive interpolation filter used for calculating a pixel value of a sub pixel to be interpolated between full pixels in a two-dimensional array, based on pixel values of the full pixels, said apparatus comprising:

• a motion estimation unit configured to estimate at sub-pel resolution, for each of blocks constituting a current picture, a motion of an image of the block from a reference picture as a motion vector;
• an identification unit configured to identify at least one block having a motion vector specifying a sub-pel position on the reference picture from among the blocks having motion vectors with sub-pel resolution estimated by said motion estimation unit, the sub-pel position having a predetermined relative positional relationship with a neighboring full pixel;
• and
• a determination unit configured to determine a filter coefficient of the sub-pel position based on an image of the at least one block of the current picture identified by said identification unit and an image of at least one block of the reference picture specified by the motion vector of the at least one block identified by said identification unit.

A program for determining a filter coefficient of a two-dimensional adaptive interpolation filter that is used for calculating a pixel value of a sub pixel to be interpolated between full pixels in a two-dimensional array, based on pixel values of the full pixels, said program causing a computer to execute:

• a motion estimating step of estimating at sub-pel resolution, for each of blocks constituting a current picture, a motion of an image of the block from a reference picture as a motion vector;
• an identifying step of identifying at least one block having a motion vector specifying a sub-pel position on the reference picture from among the blocks having motion vectors with sub-pel resolution estimated in the motion estimating step, the sub-pel position having a predetermined relative positional relationship with a neighboring full pixel;
• and
• a determining step of determining a filter coefficient of the sub-pel position based on an image of the at least one block identified in the identifying step and an image of at least one block of the reference picture specified by the motion vector of the at least one block identified in the identifying step.

An integrated circuit which determines a filter coefficient of a two-dimensional adaptive interpolation filter used for calculating a pixel value of a sub pixel to be interpolated between full pixels in a two-dimensional array, based on pixel values of the full pixels, said integrated circuit comprising:

• a motion estimation unit configured to estimate at sub-pel resolution, for each of blocks constituting a current picture, a motion of an image of the block from a reference picture as a motion vector;
• an identification unit configured to identify at least one block having a motion vector specifying a sub-pel position on the reference picture from among the blocks having motion vectors with sub-pel resolution estimated by said motion estimation unit, the sub-pel position having a predetermined relative positional relationship with a neighboring full pixel;
• and
• a determination unit configured to determine a filter coefficient of the sub-pel position based on an image of the at least one block of the current picture identified by said identification unit and an image of at least one block of the reference picture specified by the motion vector of the at least one block identified by said identification unit.