Method and apparatus for intra prediction with interpolation

Abstract

An improved method of performing intra prediction for encoding or decoding uses interpolation such that substitute samples are found for samples to be used in the interpolation calculation that lie outside a normal reference range. The substitute samples can be repeated end samples from the bottom of a reference portion to the left of the target block, or right samples of a reference portion above the target block. An encoder can signal to a decoder whether to use intra prediction or interpolation prediction.

1 .- 13 . (canceled) 
     
     
         14 . A method, comprising:
 determining whether to encode a block in a video image using intra prediction or intra prediction with pixel interpolation, wherein intra prediction with pixel interpolation comprises using a linear interpolation of a neighboring reference pixel from a top reference section above the block and a neighboring reference pixel from a left reference section left of the block;   on condition it is determined to use intra prediction with pixel interpolation:   identifying a prediction mode for the block, the prediction mode having a particular direction of prediction;   determining, for the identified prediction mode, whether a reference sample to be used for the interpolation is excluded from the left reference section for performing the intra prediction with pixel interpolation in the particular direction; and   on condition it is determined that the reference sample is excluded from the left reference section, performing the intra prediction with pixel interpolation in the particular direction using a substitute reference sample,   wherein the substitute reference sample is determined from a first reference sample corresponding to a width of the block in the top reference section and a second reference sample corresponding to a sum of the width and a height of the block in the left reference section.