The Joint Bi-level Image Experts Group jbig, an international study group a liated with iso iec and itut, is in the process of drafting a new standard for lossy and lossless compression of bi-level images. The new standard, informally referred to as jbig2, will support model-based coding for text and halftones to permit compression ratios up to three times those of existing standards for lossless compression. jbig2 will also permit lossy preprocessing without specifying how it is to be done. In this case compression ratios up to eight times those of existing standards may beobtained with imperceptible loss of quality. It is expected that jbig2 will become an International Standard by 2000.

We present a new image compression technique called \DjVu " that is speci cally geared towards the compression of high-resolution, high-quality images of scanned documents in color. This enables fast transmission of document images over low-speed connections, while faithfully reproducing the visual aspect of the document, including color, fonts, pictures, and paper texture. The DjVu compressor separates the text and drawings, which needs a high spatial resolution, from the pictures and backgrounds, which are smoother and can be coded at a lower spatial resolution. Then, several novel techniques are used to maximize the compression ratio: the bi-level foreground image is encoded with AT&T's proposal to the new JBIG2 fax standard, and a new wavelet-based compression method is used for the backgrounds and pictures. Both techniques use a new adaptive binary arithmetic coder called the Z-coder. A typical magazine page in color at 300dpi can be compressed down to betwe e n 4 0 t o 6 0 K B , a p p r o ximately 5 to 10 times better than JPEG for a similar level of subjective quality. A real-time, memory e cient v ersion of the decoder was implemented, and is available as a plug-in for popular web browsers.

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We present a new method for lossless image compression that gives compression comparable to JPEG lossless mode with about ve times the speed. Our method, called FELICS, is based on a novel use of two neighboring pixels for both prediction and error modeling. For coding we use single bits, adjusted binary codes, and Golomb or Rice codes. For the latter we present and analyze a provably good method for estimating the single coding parameter.