Linwei Zhu, Yun Zhang, Sam Kwong, Xu Wang, and Tiesong Zhao

IEEE Transactions on Broadcasting (IEEE T-BC), Sep. 2017

The latest video compression standard, High Efficiency Video Coding (HEVC), has greatly improved the coding efficiency compared to the predecessor H.264/AVC. However, equipped with the quadtree structure of coding tree unit partition and other sophisticated coding tools, HEVC brings a significant increase in the computational complexity. To address this issue, a coding unit (CU) decision method based on fuzzy support vector machine (SVM) is proposed for rate-distortion-complexity (RDC) optimization, where the process of CU decision is formulated as a cascaded multi-level classification task...

Yun Zhang, Zhaoqing Pan, Na Li, Xu Wang, Gangyi Jiang, and Sam Kwong

IEEE Transactions on Circuits System and Video Technology (IEEE T-CSVT), Aug. 2017, DOI:10.1109/TCSVT.2017.2747659

High Efficiency Video Coding (HEVC) INTRA coding improves compression efficiency by adopting advanced coding technologies, such as multi-level quad-tree block partitioning and up to 35-mode INTRA prediction. However, it significantly increases the coding complexity, memory access and power consumption, which goes against its widely applications, especially for ultra-high definition and/or mobile video applications. To tackle this problem, we propose an effective data driven Coding Unit (CU) size decision approaches for HEVC INTRA coding, which consists of two stages of Support Vector Machine based fast INTRA CU size decision schemes at four CU decision layers. At the first stage classification, a three output classifier with offline learning is developed to early terminate the CU size decision or early skip checking the current CU depth. As for the samples that neither early skipped nor early terminated, the second stage of binary classification, which learns online from previous coded frames, is proposed to further refine the CU size decision. Representative features for the CU size decision are explored...

Sudeng Hu, Lina Jin, Hanli Wang, Yun Zhang, Sam Kwong, and C.-C. Jay Kuo

IEEE Transactions on Circuits and System for Video Technology (IEEE T-CSVT), Vol.27, No.9 pp.1844-1855, Sep. 2017

Object quality assessment for compressed video is critical to various video compression systems that are essential in the video delivery and storage. Although mean squared error (MSE) is computationally simple, it may not be accurate to reflect the perceptual quality of compressed videos, which are also affected dramatically by the characteristics of the human visual system (HVS), such as contrast sensitivity, visual attention, and masking effect. In this paper, a video quality metric is proposed based on perceptually weighted MSE. A low-pass filter is designed to model the contrast sensitivity...

Linwei Zhu, Yun Zhang, Zhaoqing Pan, Ran Wang, Sam Kwong, and Zongju Peng

IEEE Transactions on Broadcasting (IEEE T-BC), May. 2017.

High Efficiency Video Coding (HEVC) improves the compression efficiency at the cost of high computational complexity by using the quad-tree coding unit (CU) structure and variable prediction unit (PU) modes. To minimize the HEVC encoding complexity while maintaining its compression efficiency, a binary and multi-class support vector machine (SVM)-based fast HEVC encoding algorithm is presented in this paper. First, the processes of recursive CU decision and PU selection in HEVC are modeled as hierarchical binary classification and multi-class classification structures...

Na Li, Yun Zhang, Wenhan Luo, and Ning Guo

Neurocomputing, Elsevier, May. 2017.

Group motion direction, which is composed of instant consistent motions, is an interesting property in group dynamics. Understanding the instant group motion direction is a key component of crowd analysis and has a wide range of applications, especially for improving group detection in crowd. In this study, independent from group detection methods, we propose an instant group motion refining framework based on group motion direction. We show that instant group motion direction can be systematically quantified by intra-group motion consistency. This is achieved by proposing two instant...

Xu Wang, Lei Cao, Yingying Zhu, Yun Zhang, Jianmin Jiang, Sam Kwong

IEEE International Conference on Image Processing (ICIP'2017), Beijing, China, Sept, 2017, (Accepted)

In this paper, we present the results of a recent large-scale subjective study of image quality on a collection of screen contents distorted by a variety of application-relevant processes. With the development of multi-device interactive multimedia applications, metrics to predict the visual quality of screen content images (SCIs) as perceived by subjects are becoming fundamentally important. For developing the objective image quality assessment (IQA) method, there is a need...

Yun Zhang, Na li, Zongju Peng

International Conference on Cloud Computing and Security (ICCCS2017), Lecture Notes in Computer Sciences, Nanjing, Jun. 2017, (Accepted)

Cloud video transcoding enable to convert the video standards and properties from one to another so as to adapt to different user end devices and network capacity, especially in sharing massive video contents in cloud environment. High Efficiency Video Coding (HEVC) and H.264/Advanced Video Coding are two recent high performance video coding standards that are widely used and co-existing in video industry. Video transcoding is desirable to bridge the standard gap. To effectively transcode video stream from H.264/AVC to HEVC for higher compression efficiency and meanwhile maintaining low computational...