Minyoung Eom

Fast Mode Decision for Intra Prediction in H.264/AVC Encoder

The H.264/AVC video coding standard uses the rate distortion optimization (RDO) method to improve the compression performance in the intra prediction. Whereas the computational complexity is increased comparing with previous standards due to this method, even though this standard selects the best coding mode for the current macroblock. In this paper, a fast intra mode decision algorithm for H.264/AVC encoder based on dominant edge direction (DED) is proposed. The algorithm uses the approximation of discrete cosine transform (DCT) coefficient formula. By detecting the DED before intra prediction, 3 modes instead of 9 modes are chosen for RDO calculation to decide the best mode in the 4 times 4 luma block. For the 16 times 16 luma and the 8 times 8 chroma, instead of 4 modes, only 2 modes are chosen. Experimental results show that the computation time of the proposed algorithm is decreased to about 71% of the full search method in the reference code with negligible quality loss.

Scene Change Detection using Edge Direction based on Intra Prediction Mode in H.264/AVC Compression Domain

This paper presents a novel scene change detection method using edge direction based on intra prediction mode in H.264/AVC. When scene change occurs, there is less temporal correlation between frames. Therefore, most of macro-blocks are encoded in intra mode. Using this property, the proposed method calculates the percentage of intra mode blocks in each predictive frame in order to get candidates of scene change frames. To find accurate scene changes, we generate an edge histogram of each candidate with eight prediction directions of intra prediction mode in H.264/AVC. We detect scene change frames with l1 -norm of edge histograms. The experimental results show that the proposal method is efficient and robust

Variable-lenth code based on an order complexity

In this paper, we introduce new codeword sets based on order complexity (OC) which measures uncertainty of the order having each permutation string. The proposed codeword sets are generated by two procedures: Indexing and B-transform. Indexing is that a smaller positive integer is mapped to a permutation string whose OC is lower. B-transform plays role of generating a binary string from the permutation string on reflecting the OC, that is, low OC is represented by short binary strings and high OC is represented by long binary strings. The sets of these binary strings are our proposed codeword sets (B-codes). The B-codes are the uniquely decipherable complete variable length codeword sets and have shorter codeword length than most other variable length codes for values of 4 or more for the finite integers.

Fast Sub-pixel Search Control by using Neighbor Motion Vector in H.264

We propose a novel fast sub-pixel search control algorithm for H.264 encoder by using neighbor motion vectors. This fast sub-pixel search control algorithm cuts down the motion estimation time by referring neighbor motion vectors and the current integer motion vector. This algorithm can also improve the performance of the motion estimation time more by merging other fast search algorithms with its independent discrimination.

Edge Histogram Descriptor in Wavelet Domain Based on JPEG2000

Due to the decoding procedure and filtering for edge detection, the feature extraction process of MPEG-7 Edge Histogram Descriptor (EHD) is time-consuming and computationally expensive. We proposed the fast EHD generation method in wavelet domain of JPEG2000 images. Experimental results demonstrate the advantage of this method over EHD.