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22 lines
1.5 KiB
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22 lines
1.5 KiB
Text
This software package contains an implementation of JPEG-LS, the emerging
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lossless/near-lossless compression standard for continuous-tone images being
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developed by ISO/IEC JTC1/SC29/WG1 (draft document FCD14495 as of November
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1997). The names of the executables in the software package derive from the
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acronym LOCO, as the core of the new standard is based on the LOCO-I algorithm
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(LOw COmplexity LOssless COmpression for Images) developed at Hewlett-Packard
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Laboratories (reference: M. Weinberger, G. Seroussi, G. Sapiro, "LOCO-I: A Low
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Complexity, Context-Based, Lossless Image Compression Algorithm," Proc. IEEE
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Data Compression Conference, Snowbird, Utah, March-April 1996).
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The term "near-lossless compression" refers to a lossy algorithm for which each
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decompressed image sample differs from the corresponding original image sample
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by not more than a pre-specified value, the (usually small) "loss." Lossless
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compression corresponds to loss=0. Even though the term "continuous-tone image"
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refers in principle to any image whose components have more than one bit per
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sample, palletized images may require a reordering of the color palette for best
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compression results using LOCO-I on the array of color indices. This
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functionality is not implemented in the present software, although it is
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supported by the new standard, and is easy enough to implement with the tools
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given. Notice, however, that LOCO-I and JPEG-LS were not designed, and might not
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give optimal performance, for images that have been palletized through
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dithering.
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