Computation reduction in high-efficiency video coding based on the similarity of transform unit blocks

Zong Yi Chen, Jiunn Tsair Fang, Chung Shian Chiang, Pao Chi Chang

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The new video coding standard, high-efficiency video coding, adopts a quadtree structure to provide variable transform sizes in the transform coding process. The heuristic examination of transform unit (TU) modes substantially increases the computational complexity, compared to previous video coding standards. Thus, efficiently reducing the TU candidate modes is crucial. In the proposed similarity-check scheme, sub-TU blocks are categorized into a strongly similar case or a weakly similar case, and the early TU termination or early TU splitting procedure is performed. For the strongly similar case, a property called zero-block inheritance combined with a zero-block detection technique is applied to terminate the TU search process early. For the weakly similar case, the gradients of residuals representing the similarity of coefficients are used to skip the current TU mode or stop the TU splitting process. In particular, the computation time is further reduced because all the required information for the proposed mode decision criteria is derived before performing the transform coding. The experimental results revealed that the proposed algorithm can save ~64% of the TU encoding time on average in the interprediction, with a negligible rate-distortion loss.

Original languageEnglish
Article number061105
JournalJournal of Electronic Imaging
Issue number6
StatePublished - Nov 2014


  • complexity reduction
  • fast algorithm
  • high-efficiency video coding
  • mode decision
  • transform unit


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