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# Fax2 - QM-Coder T he arithmetic coders used in JPEG JPEG...

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QM-Coder T he arithmetic coders used in JPEG, JPEG 2000 and JBIG are called QM-coder. It handles only binary strings or input and it is designed for simplicity and speed. It uses approximation for multiplication operation, fixed-precision integer arithmetic with renormalization of the probability interval from time to time. The main idea of the QM-coder is to classify the input bit as M ore P robable S ymbol ( MPS) and L ess P robable S ymbol ( LPS) . Before the next bit is input, the QM-coder uses a statistical model (using a context, typically a two- dimensional context of black and white pixel in an image) to predict which one of the bits (0 or 1) will be the MPS . If the predicted MPS bit does not match with the actual bit, then the QM-coder will classify this as LPS ; otherwise, it will continue to be classified as MPS . The output of the coder is simply a stream of MPS or LPS , which are assigned probability values dynamically to be used by the simplified arithmetic coder. The decoder has only the knowledge of whether the next predicted bit is MPS or LPS . It uses the same statistical model

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Fax2 - QM-Coder T he arithmetic coders used in JPEG JPEG...

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