Video prediction encoding device, video prediction encoding method, video prediction decoding device and video prediction decoding method

A moving picture prediction decoding method executed by a moving picture prediction decoding device, the moving picture prediction decoding method comprising:

• a decoding step of decoding, from encoded compression data for a plurality of divided blocks, an intra prediction mode indicating an intra-picture prediction method of a target block to be decoded and a compressed residual signal;
• a prediction signal generation step of generating an intra-picture prediction signal using the intra prediction mode and previously reconstructed reference samples located adjacent to the target block;
• a residual signal restoration step of restoring a reconstructed residual signal of the target block from the compressed residual signal;
• and
• a block storage step of restoring a pixel signal of the target block by adding the prediction signal to the reconstructed residual signal, and storing the reconstructed pixel signal of the target block to be used as reference samples of a subsequent target block, wherein
• in the prediction signal generation step, a series of adjacent reference samples is derived from previously reconstructed blocks, which are stored and neighbour the target block, an interpolation process is performed between two or more key reference samples located at predetermined positions among the reference samples for generating interpolated reference samples, and the intra-picture prediction signal is generated by extrapolating the interpolated reference samples based on the intra prediction mode, and
• in the prediction signal generation step, if a block size of the target block is N×N, the series of adjacent reference samples is an array ref[x] (where x is an integer of 0 to 4N), and if ref[2N] is a key reference sample AL and ref[4N] is a key reference sample AR, the interpolation process of a reference sample ref[2N+i] (where i is an integer of 1 to 2N−1) is based on a formula ((2N−i)*AL+i*AR+N)/2N.