Fast Intra Prediction in the Transform Domain

• Main Authors: Chanyul Kim, O'Connor, N.E., Yunje Oh
• Format: Conference Proceeding
• Language: English
• Subjects: AC generators; Automatic voltage control; Computational complexity; DC generators; Discrete cosine transforms; Extrapolation; Filtering; Low pass filters; Prediction algorithms; PSNR
• ISSN: 1068-0314; 2375-0359
• DOI: 10.1109/DCC.2009.26

The paper reports a new fast intra prediction algorithms based on separating the transformed coefficients of neighboring blocks. The prediction blocks are obtained from the transformed and quantized neighboring blocks that generate minimum distortion for each DC and AC coefficients. To obtain fast coding with comparable coding efficiency compared to H.264/AVC, we present the full block search prediction (FBSP) and the edge based distance prediction (EBDP). These are immune to both the intra prediction error and the drift propagation; in addition, do not require a low pass filtering named extrapolation and mode decisions to obtain a prediction block. In FBSP, eight neighbor blocks (B (i-j) ) are chosen to be candidates by observing the edge direction of the current block ((0,0)), where (i,j) are relative displacement position to the current block denoted as (i,j) G {(0,-1), (-1, 0), (-1, -1), (+1, -1), (-2, -1), (-1, -2), (+2, -1), (+1, -2)}, and the prediction block can be obtained by combining DC and AC coefficients of a neighboring block generating minimum distortion of residues. In EBSP, the edge directions of the current block are estimated from DCT coefficients, and intuitionally the prediction block is selected by observing the minimum edge distance (difference) compared to the current block without any distortion measurements. We have applied the proposed algorithms to MPEG test sequences which are Foreman, Hall, Mother and Daughter and Mobile. A PSNR (peak signal to noise ratio) gain of -2 to +0.8dB is observed at various bit rates shown in Figure l(a)(b), where + indicates PSNR degradation, - denotes PSNR gain compared to H.264/AVC intra coding. In case of a complex scene in terms of edges, the prediction error could be more dominant rather than one caused by quantization, the proposed method shows the same or better coding efficiency due to its insensitivity of the prediction error and the drift propagation. Analyzing of computational complexity, the proposed algorithms require less than 15% complexity compared to low complexity mode of H.264/AVC in Figure 1(c) since they does not perform an extrapolation and mode decisions which generates intensive computational complexity in H.264/AVC intra coding.