数字电视关键技术探讨

在模拟电视向数字电视转变的进程中,数字化相关技术至关重要.介绍了数字电视所必须使用的几项关键技术.     

基于区域重要性的嵌入式零树小波编码

在分析了JPEG2000中的感兴趣区域编码算法的基础上,针对其不足提出了一种基于区域重要性的嵌入式零树小波编码方法。算法无须修改小波系数值而用域值控制感兴趣区的恢复质量,并基于此修改了零树编码中的幅值编码。为了使得符号流更适合游程编码修改了零树编码中的扫描顺序,获得了较好的实验结果。     

纠错码在数字电视信道编码中的应用

介绍了方兴未艾的数字电视的发展，特点、信道编码方面的世界标准以及我国的研究成果。比较了世界三大标准在信道编码方面的特点。优势,介绍了广泛使用的R—S码，提出了我国制定标准的考虑以及未来的发展。     

基于地理编码的北京市城乡规划信息资源整合研究

城市地理编码是“数字城市”空间信息基础设施的重要内容，是实现城市信息共享与交换的支撑技术。北京市地理编码标准制定工作通过确定空间定位参考体系和空间单元，采用空间解析、空间关联及空间参照的实施方法，实现地理编码在城市规划信息资源整合中的应用，为城多规划信息资源共享带来契机。     

Extended ternary sequences and two-dimensional coding collimators based on them

A new extensive class of one-dimensional ternary (−1, 0, +1)-sequences, called extended ternary sequences, is proposed, which enables radiation-physics experiments to be more completely optimized and enables problems of emission planar tomography to be solved more effectively using code-based integrated measurement systems. __________ Translated from Izmeritel'naya Tekhnika, No. 8, pp. 62–68, August, 2008     

基于模型的H263＋可扩展性编码

提出了基于模型的视频时空可扩展性编码方法，即根据人眼视觉敏感程度的不同，将视频中的每帧图象根据模型划分为程度不同的区域，对每一个区域分配不同的时间和空间分辨率，以期在极低码率的传送环境中保证人眼敏感区域的图象质量和传送效率。     

基于Intra帧刷新的差错控制新方法

面向IP网,本文分析了传统的基于帧内编码(Intra)帧周期刷新机制的性能,针对其编码效率低的缺点,提出了基于敏感度和反馈信息刷新的两种新方法.这两种方法不仅保持了周期刷新对差错的自恢复能力,而且在很大程度上改善了编码效率.     

An integrated FEC coding scheme for ATM transmission over regenerative satellite networks

The application of asynchronous transfer mode (ATM) on both wireless and satellite networks requires system adaptation. This adaptation has to improve the overall system's performance, and achieve high quality‐of‐service classes approaching that for fibre‐optic communications. In this paper, a new integrated forward‐error‐correction (FEC) coding scheme is introduced for ATM transmission over regenerative satellite networks. The proposed FEC scheme is a concatenation of two Reed–Solomon codes tailored for the header and payload parts of the ATM cell. This integrated coding scheme is shown to significantly improve the cell loss ratio as compared to the standard CRC code used in the ATM cell header. We obtain both upper and lower performance bounds for the concatenated code and check their accuracy when compared to exact system's performance. Both analytical and simulation results show that a cell loss ratio and bit‐error rate (BER) of 10^?25 and 10^?7 can be, respectively, achieved with minimum delay requirements on the SATCOM link. Finally, an approximation for the system's throughout is obtained. It is shown that using a hybrid selective‐repeat automatic‐repeat‐request (SR‐ARQ) with the RS code, a large throughput of approximately 0.843 can be achieved at BERs lower than 10^?7 for data services. Copyright © 2005 John Wiley & Sons, Ltd.     

Segment-based coding of color images

Based on the idea of second generation image coding, a novel scheme for coding still images is presented. At first, an image was partitioned with a pulse-coupled neural network; and then an improved chain code and the 2D discrete cosine transform was adopted to encode the shape and the color of its edges respectively. To code its smooth and texture regions, an improved zero-trees strategy based on the 2nd generation wavelet was chosen. After that, the zero-tree chart was selected to rearrange quantified coefficients. And finally some regulations were given according to psychology of various users. Experiments under noiseless channels demonstrate that the proposed method performs better than those of the current one, such as JPEG, CMP, EZW and JPEG2000. Supported by the Senior University Technology Innovation Essential Project Cultivation Fund Project (Grant No. 706028) and the Natural Science Fund of Jiangsu Province (Grant No. BK2007103)     

Fundamental error analysis and geometric interpretation for block truncation coding techniques

Various variants and hybrid approaches evolved from the origin of Delp and Mitchell's block truncation coding (BTC) or moment preserving quantizer (MPQ) have formed a niche as an effective and simple image compression methodology with attractive coding performance achieved at moderate bitrates. As BTC is still lacking a fundamental error analysis, in this paper we present some fundamental insights regarding one-bit (or two-level) BTC's truncation error by providing mathematical analysis as well as novel geometric interpretation. We further show that the mean-square error (MSE) of Lema and Mitchell's absolute moment block truncation coding (AMBTC) is always bounded below (i.e., less than or equal to) that of BTC. Therefore, with additional advantages in computation and implementation, AMBTC is always superior. Furthermore, we developed a new adaptive equal sign position optimization (ESPO) algorithm for optimum pixel classification. Our quantization error analysis shows that incorporating the ESPO algorithm into conventional AMBTC or BTC achieves minimum MSE in either case.