Method and device for interpolating images by using a smoothing interpolation filter
Provided are a method of interpolating an image by determining interpolation filter coefficients, and an apparatus for performing the same. The method includes: differently selecting an interpolation filter, from among interpolation filters for generating at least one sub-pel-unit pixel value located between integer-pel-unit pixels, based on a sub-pel-unit interpolation location and a smoothness; and generating the at least one sub-pel-unit pixel value by interpolating, using the selected interpolation filter, pixel values of the integer-pel-unit pixels.
1. An apparatus for motion compensation, the apparatus comprising:
a luma interpolation filtering unit which is configured for determining, in a luma reference picture, a luma reference block for prediction of a current block, by using a luma motion vector of the current block, and generating a luma sample of a 2/4-pixel location included in the luma reference block by applying an 8-tap filter to luma samples of an integer pixel location of the luma reference picture; and
a chroma interpolation filtering unit which is configured for determining, in a chroma reference picture, a chroma reference block for prediction of a current block, by using a chroma motion vector of the current block, and generating at least one chroma sample of at least one of ⅛, 2/8 and ⅜-pixel locations included in the chroma reference block by applying a 4-tap filter to chroma samples of an integer pixel location of the chroma reference picture,
wherein the 8-tap filter comprises eight filter coefficients,
the 4-tap filter comprises four filter coefficients, and
among eight filter coefficients of the 8-tap filter for generating the luma pixel of the 2/4-pixel, four consecutive filter coefficients including a first filter coefficient are arranged in reverse order against four consecutive filter coefficients including a last filter coefficient.
2. The apparatus of claim 1 , wherein the luma interpolation filtering unit is configured for scaling the luma sample generated by applying the 8-tap filter by using a luma scaling factor that a sum of coefficients of the 8-tap filter is 1.
3. The apparatus of claim 1 , wherein the chroma interpolation filtering unit is configured for scaling the chroma sample generated by applying the 4-tap filter by using a chroma scaling factor that a sum of coefficients of the 4-tap filter is 1.