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jbig2官方技术文档-fcd14492.pdf
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详细说明： jbig2官方技术文档。 找了很久才找到的， 与大家共享。 有需要的朋友下载。 下面是简介原文： 0 Introduction This Recommendation j International Standard, informally called JBIG2, defines a coding method for bi-level images (e.g., black and white printed matter). These are images consisting of a single rectangular bit plane, with each pixel taking on one of just two possible colours. Multiple colours are to be handled using an appropriate higher level standard such as ITU-T Recommendation T.44. It is being drafted by the Joint Bi-level Image Experts Group (JBIG), a “Colla borative Team”, established in 1988, that reports both to ISO/IEC JTC 1/SC29/WG1 and to ITU-T/SG8. Compression of this type of image is also addressed by existing facsimile standards, for example by the compression algorithms in ITU-T Recommendations T.4 (MH,MR), T.6 (MMR), T.82 (JBIG1), and T.85 (Application profile of JBIG1 for facsimile). Besides the obvious facsimile application, JBIG2 will be useful for document storage and archiving, coding images on the World Wide Web, wireless data transmission, print spooling, and even teleconferencing. As the result of a process that ended in 1993, JBIG produced a first coding standard formally designated ITUT Recommendation T.82 j International Standard ISO/IEC 11544, which is informally known as JBIG or JBIG1. JBIG1 is intended to behave as lossless and progressive (lossy-to-lossless) coding. Though it has the capability of lossy coding, the lossy images produced by JBIG1 have significantly lower quality than the original images because the number of pixels in the lossy image cannot exceed one quarter of those in the original image. On the contrary, JBIG2 was explicitly prepared for lossy, lossless, and lossy-to-lossless image compression. The design goal for JBIG2 was to allow for lossless compression performance better than that of the existing standards, and to allow for lossy compression at much higher compression ratios than the lossless ratios of the existing standards, with almost no visible degradation of quality. In addition, JBIG2 allows both quality-progressive coding, with the progression going from lower to higher (or lossless) quality, and content-progressive coding, successively adding different types of image data (for example, first text, then halftones). A typical JBIG2 encoder decomposes the input bi-level image into several regions and codes each of the regions separately using a different coding method. Such content-based decomposition is very desirable especially in interactive multimedia applications. JBIG2 can also handle a set of images (multiple page document) in an explicit manner. As is typical with image compression standards, JBIG2 explicitly defines the requirements of a compliant bitstream, and thus defines decoder behavior. JBIG2 does not explicitly define a standard encoder, but instead is flexible enough to allow sophisticated encoder design. In fact, encoder design will be a major differentiator among competing JBIG2 implementations. Although this document is phrased in terms of actions to be taken by decoders to interpret a bitstream, any decoder that produces the correct result (as defined by those actions) is compliant, regardless of the actions it actually takes. Annexes A, B, C, D, E are normative, and thus form an integral part of this Specification. Annexes F, G, H, I and J are informative, and thus do not form an integral part of this Specification. ...展开收缩
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