Effective CU Size Decision for HEVC Intracoding

In high efficiency video coding (HEVC), the tree structured coding unit (CU) is adopted to allow recursive splitting into four equally sized blocks. At each depth level (or CU size), it enables up to 35 intraprediction modes, including a planar mode, a dc mode, and 33 directional modes. The intrapre...

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Bibliographic Details
Published in:IEEE transactions on image processing 2014-10, Vol.23 (10), p.4232-4241
Main Authors: Shen, Liquan, Zhang, Zhaoyang, Liu, Zhi
Format: Article
Language:English
Subjects:
Algorithm design and analysis
Algorithms
Coding
Complexity
Computation
Computational complexity
Encoding
Heuristic
Homogeneity
Image coding
Prediction algorithms
Searching
Surface layer
Texture
Video coding
Video compression
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Summary:In high efficiency video coding (HEVC), the tree structured coding unit (CU) is adopted to allow recursive splitting into four equally sized blocks. At each depth level (or CU size), it enables up to 35 intraprediction modes, including a planar mode, a dc mode, and 33 directional modes. The intraprediction via exhaustive mode search exploited in the test model of HEVC (HM) effectively improves coding efficiency, but results in a very high computational complexity. In this paper, a fast CU size decision algorithm for HEVC intracoding is proposed to speed up the process by reducing the number of candidate CU sizes required to be checked for each treeblock. The novelty of the proposed algorithm lies in the following two aspects: 1) an early determination of CU size decision with adaptive thresholds is developed based on the texture homogeneity and 2) a novel bypass strategy for intraprediction on large CU size is proposed based on the combination of texture property and coding information from neighboring coded CUs. Experimental results show that the proposed effective CU size decision algorithm achieves a computational complexity reduction up to 67%, while incurring only 0.06-dB loss on peak signal-to-noise ratio or 1.08% increase on bit rate compared with that of the original coding in HM.
ISSN:1057-7149
1941-0042
DOI:10.1109/TIP.2014.2341927