Method and apparatus for performing interpolation based on transform and inverse transform
Provided are a method and apparatus for interpolating an image. The method includes: selecting a first filter, from among a plurality of different filters, for interpolating between pixel values of integer pixel units, according to an interpolation location; and generating at least one pixel value of at least one fractional pixel unit by interpolating between the pixel values of the integer pixel units by using the selected first filter.
1. A method of motion compensation, the method comprising:
determining, in a luma reference picture, a luma reference block for prediction of a current block by using a luma motion vector;
generating a luma sample of a 2/4-pixel location included in the luma reference block, by applying an 8-tap interpolation filter to luma samples of an integer pixel location of the luma reference picture; and
generating a luma sample of a ¼-pixel location or a ¾-pixel location included in the luma reference block, by applying an interpolation filter to the luma samples of the integer pixel location of the luma reference picture without using the generated luma sample of the 2/4-pixel location,
wherein the 8-tap interpolation filter comprises eight filter coefficients,
the interpolation filter for generating the luma sample of the ¼-pixel location or the ¾-pixel location comprises a plurality of filter coefficients, and
among the plurality of filter coefficients of the interpolation filter for generating the luma sample of the ¼-pixel location or the ¾-pixel location, at least two filter coefficients are different from each other.
2. The method of claim 1 , wherein the generating of the luma sample of a 2/4-pixel location comprises scaling the luma sample generated by applying the 8-tap interpolation filter by using a luma scaling factor so that a sum of coefficients of the 8-tap interpolation filter is 1,
wherein the luma scaling factor is 64.
3. The method of claim 1 , wherein:
an image is split into a plurality of maximum coding units,
a maximum coding unit, among the plurality of maximum coding units, is hierarchically split into one or more coding units of depths including at least one of a current depth and a lower depth according to split information indicating whether a coding unit is split,
when the split information indicates a split for the current depth, a coding unit of the current depth is split into four coding units of the lower depth, independently from neighboring coding units, and
when the split information indicates a non-split for the current depth, prediction units are obtained from the coding unit of the current depth.