Huifeng Shen

Virtualized Screen: A Third Element for Cloud–Mobile Convergence

Mobile and cloud computing have emerged as the new computing platforms and are converging into a powerful cloud-mobile computing platform. This article envisions a virtualized screen as a new dimension in such a platform to further optimize the overall computing experience for users. In a virtualized screen, screen rendering is done in the cloud, and delivered as images to the client for interactive display. This enables thin-client mobile devices to enjoy many computationally intensive and graphically rich services. Technical challenges are discussed and addressed. Two novel cloud-mobile applications, Cloud Browser and Cloud Phone, are presented to demonstrate the advantages of such a virtualized screen.

Browser-friendly hybrid codec for compound image compression

In this paper, we present a browser-friendly hybrid JPEG/PNG codec for compound images. First we employ a simple yet efficient block classification algorithm to identify the blocks to pictorial and textural ones. And then JPEG is used to encode the pictorial blocks and PNG is used for textual blocks. Our evaluation results show that our codec significantly outperforms JPEG and PNG in terms of rate-distortion performance, and also it outperforms JPEG, JPEG2000 and DjVu in terms of visual quality. Moreover, since JPEG and PNG are naturally supported by modern browsers, the coded images generated from our proposed coder can be natively supported by browsers and possible to be widely deployed in Web applications.

A proxy-based mobile web browser

In this paper, we present a proxy-based mobile web browser with rich experiences. We use the server-side web parsing and rendering to leverage the browser computing logic. We use a composite screen format to represent the display of the web content, incorporating the web background screen and the dynamic web objects. And then we employ a slice-based screen encoding scheme to efficiently compress the web background screen. Besides the display screen of the web content, we also send the side information of the web objects to enable the designed object-level interaction mechanisms. The experimental results show that our browser can achieve the superior browsing speed, compared with the native browser and yield much better visual quality than the existing proxy-based browser

A low-complexity screen compression scheme

This paper presents a block-based low-complexity screen compression scheme. In this scheme, the input screen is split into non-overlapping blocks which are classified as pictorial blocks and textual blocks. We design a low-complexity yet efficient algorithm to compress the textual blocks. We use base colors plus escape pixels to represent and quantize the text pixels, and such quantization mechanism not only achieves high compression efficiency but also keeps low encoding/decoding complexity. We also propose the two-direction predictive index coding and hierarchical pattern coding technologies to utilize the local spatial correlation and the global pattern correlation for text pixels. In addition, to utilize the correlation between the luminance and chrominance channels, we propose a joint-channel index coding method to further improve the compression efficiency. The compression efficiency and complexity of the proposed method is evaluated against the popular image codecs JPEG/JPEG200 and PNG, a recent published screen compression scheme HJPC as well as the popular video codec H.264.

A low-latency transmission scheme for interactive screen sharing

Screen is becoming a new dimension in cloud computing platforms, and low latency screen sharing in unreliable networks is becoming more and more important. Due to the different characteristics between the screen codecs and video codecs, current transmission technologies on low-latency video streaming cannot be directly applied to screen sharing. So in this paper we first theoretically analyze the difference in latency performance between ARQ and FEC for the UDP-based screen sharing. Then, considering the characteristics of the main-stream screen codecs, we propose an improved ARQ scheme to decrease the transmission latency. The experimental results show that the proposed system achieves better latency performance than the popular systems.

Effective hand segmentation and gesture recognition for browsing web pages on a large screen

Modern digital family technology enables people surf the Internet and watch videos via a large screen. This paper proposes an effective scheme for using hand gestures rather than the common remote controllers to browse the web pages on a large TV screen. The proposed scheme models four gesture modes: mouse mode, scroll mode, zoom mode and input mode to help the user browse Web pages naturally and comfortably. Then we combine RGB, depth, motion information and face detection to achieve accurate and real-time hand segmentation and gesture recognition for enabling the four gesture modes. The experiments show the proposed scheme works well in various illumination environments and complicated backgrounds with multiple moving humans. The recognition accuracy of hand shapes in the proposed scheme arrives at 98.50%, and the successful rate for visual digits input reaches 89.00%. Furthermore, the frame rate of the hand-gesture detection and recognition is about 18 fps. Thus the scheme is accurate, real-time and natural.