Jizheng Xu

Overview of the Emerging HEVC Screen Content Coding Extension

A screen content coding (SCC) extension to High Efficiency Video Coding (HEVC) is currently under development by the Joint Collaborative Team on Video Coding, which is a joint effort from the ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. The main goal of the HEVC-SCC standardization effort is to enable significantly improved compression performance for videos containing a substantial amount of still or moving rendered graphics, text, and animation rather than, or in addition to, camera-captured content. This paper provides an overview of the technical features and characteristics of the current HEVC-SCC test model and related coding tools, including intra-block copy, palette mode, adaptive color transform, and adaptive motion vector resolution. The performance of the SCC extension is compared against existing standards in terms of bitrate savings at equal distortion.

Screen Content Coding Based on HEVC Framework

Screen content like cartoons, captures of typical computer screens or video with text overlay or news ticker is an important category of video, which needs new techniques beyond the existing video coding techniques. In this paper, we analyze the characteristics of screen content and coding efficiency of HEVC on screen content. We propose a new coding scheme, which adopts a non-transform representation, separating screen content into color component and structure component. Based on the proposed representation, two coding modes are designed for screen content to exploit the directional correlation and non-translational changes in screen video sequences. The proposed scheme is then seamlessly incorporated into the HEVC structure and implemented into HEVC range extension reference software HM9.0. Experimental results show that the proposed scheme achieves up to 52.6% bitrate saving compared with HM9.0. On average, 35.1%, 29.2% and 23.6% bitrate saving are achieved with intra, random-access and low-delay configurations, respectively. The visual quality of the decoded video sequences is also significantly improved by reducing ringing artifacts around sharp edges and reserving the shape of text without blur.

Overview of the Range Extensions for the HEVC Standard: Tools, Profiles, and Performance

The Range Extensions (RExt) of the High Efficiency Video Coding (HEVC) standard have recently been approved by both ITU-T and ISO/IEC. This set of extensions targets video coding applications in areas including content acquisition, postproduction, contribution, distribution, archiving, medical imaging, still imaging, and screen content. In addition to the functionality of HEVC Version 1, RExt provide support for monochrome, 4:2:2, and 4:4:4 chroma sampling formats as well as increased sample bit depths beyond 10 bits per sample. This extended functionality includes new coding tools with a view to provide additional coding efficiency, greater flexibility, and throughput at high bit depths/rates. Improved lossless, near-lossless, and very high bit-rate coding is also a part of the RExt scope. This paper presents the technical aspects of HEVC RExt, including a discussion of RExt profiles, tools, applications, and provides experimental results for a performance comparison with previous relevant coding technology. When compared with the High 4:4:4 Predictive Profile of H.264/Advanced Video Coding (AVC), the corresponding HEVC 4:4:4 RExt profile provides up to ~25

Visual summarization of web pages

%, ~32%, and ~36% average bit-rate reduction at the same PSNR quality level for intra, random access, and low delay configurations, respectively.

Adaptive Color-Space Transform for HEVC Screen Content Coding

Visual summarization is a attractive new scheme to summarize web pages, which can help achieve a more friendly user experience in search and re-finding tasks by allowing users quickly get the idea of what the web page is about and helping users recall the visited web page. In this paper, we perform a careful study on the recently proposed visual summarization approaches, including the thumbnail of the web page snapshot, the internal image in the web page which is representative of the content in the page, and the visual snippet which is a synthesized image based on the internal image, the title, and the logo found in the web page. Moreover, since the internal image based summarization approach hardly works when the representative internal images are unavailable, we propose a new strategy, which retrieves the representative image from the external to summarize the web page. The experimental results suggest that the various summarization approaches have respective advantages on different types of web pages. While internal images and thumbnails can provide a reliable summarization on web pages with dominant images and web pages with simple structure respectively, the external images are regarded as a useful information to complement the internal images and are demonstrated very useful in helping users understanding new web pages . The visual snippet performs well on the re-finding tasks since it incorporates the title and logo which are advantageous on identifying the visited web pages.

Overview of Screen Content Video Coding: Technologies, Standards, and Beyond

This paper presents an in-loop adaptive color-space transform for the HEVC Screen Content Coding extension. In the proposed method, the prediction residual is adaptively converted into a different color space to reduce the cross-component redundancy. After the ACT, the signal is coded following the existing HEVC framework. To keep the complexity as low as possible, fixed color-space transforms that are easily implemented with shift and add operations are utilized. Significant coding gains are achieved by this method in the current HEVC Screen Content Coding reference software with no increase of decoding runtime. The proposed method has been adopted to the HEVC Screen Content Coding extension.

Visually Summarizing Web Pages Through Internal and External Images

This paper presents recent advances in screen content video coding, with an emphasis on two state-of-the-art standards: HEVC/H.265 Screen Content Coding Extensions (HEVC-SCC) by ISO/IEC Moving Picture Experts Group and ITU-T Video Coding Experts Group, and Display Stream Compression (DSC) by Video Electronics Standards Association. The HEVC-SCC enhances the capabilities of HEVC in coding screen content, while DSC provides lightweight compression for display links. Although targeting different application domains, they share some design principles and are expected to become the leading formats in the marketplace in the coming years. This paper provides a brief account of their background, key elements, performance, and complexity characteristics, according to their final specifications. As we survey these standards, we also summarize prior arts in the last decade and explore future research opportunities and standards developments in order to give a comprehensive overview of this field.

Guest Editorial Screen Content Video Coding and Applications

Visually summarizing web pages is an attractive approach that provides users an effective and friendly interface to identify desired contents at a first glance for search and re-finding tasks. Using dominant images in web pages is generally reliable for this purpose. However, dominant images are often unavailable in many web pages. To solve this problem, we first propose a new approach to summarize those web pages without any dominant images by retrieving relevant external images from the Internet. However, relevant external images are sometimes unreliable. To take the advantages of these two kinds of images, we further propose a clustering based algorithm to select the best summarization among all of internal and external images. This algorithm leverages relevance and dominance of images as the prior information. Experimental results show that our approach achieves 0.098 and 0.082 NDCG1 gain on a human labeled data set, compared with relevant external image and dominant image, respectively. Our user study also indicates that the images selected by our algorithm are useful as the summarization of web pages.

Improving screen content coding in HEVC by transform skipping

This special issue aims to present recent technical advances in screen content video coding and applications. Screen content video has recently evolved from a niche to the mainstream due to the rapid advances in mobile and cloud technologies. Real-time, low-latency transport of screen visuals between devices in the form of screen content video is becoming prevalent in many applications, e.g., wireless displays, screen mirroring, display interfaces, screen/desktop virtualization and cloud-based mobile virtual reality. Today’s commonly-used video coding methods, however, have been developed primarily with camera-captured content in mind. These new applications create an urgent need for efficient coding of screen content video, especially as the support of 4k or even 8k resolution begins to achieve mass market appeal.