电子与通信工程专业英语Unit 8 JPEG2000 Retrospective and New Developments.ppt

　　1．Introduction　　JPEG2000 is a new image compression standard developed under the auspices of ISO/IEC JTC1/SC29/WG1(commonly know as the Joint Photographic Experts Group(JPEG)committee). The standard makes use of several recent advances in compression technology to deliver superior compression performance and provides many advanced features in scalability, flexibility, and systems functionalities that outperform its predecessor, the original JPEG standard[1]. In particular, JPEG2000 uses a discrete wavelet transform (DWT) in place of the discrete cosine transform (DCT) of JPEG. It uses a sophisticated coding mechanism that supports flexible, finely embedded representation of the image so that many desirable features are provided in one single bit stream. JPEG2000 places strong emphasis on scalability to the extent that virtually all JPEG2000 bitsreams are highly scalable. This paper gives an overview of this triumph in innovations and teamwork. It gives brief introductions to the four new parts: ① Interactive Tools, Application Programming Interfaces, and Protocols(JPIP)；② Secure JPEG2000(JPWL)； ③ 3-D Data(JP3D)；④ Wireless (JPWL) that are under currently development by the JPEG committee. It attempts to summarize the lessons learned from the JPEG2000 development experience and draw some conclusions on the success factors of this important standard. 　　2．Development of JPEG2000　　1) ?Original JPEG　　The original JPEG standard, which was developed in the late 1980s, is a very successful standard in terms of its widespread use by very large number of digital imaging applications. The technology adopted in baseline JPEG at the time of its development was based on a simple, efficient 8-by-8 DCT compression algorithm that uses Huffman coding, operated in sequential mode and restricted to 8-b/pixel input. Besides its technical merits, the success enjoyed by JPEG can be attributed to the availability of the free and efficient software developed by the Independent JPEG Gr