Ricoh Corporation

Ricoh Company, Ltd.

Other

Ricoh California Research Center

James D Allen

Martin P Boliek

Edward L Schwartz

Steven M Blonstein

Michael J Gormish

Ahmad Zandi

David Geoffrey Stork

Stephen M Blonstein

John F Cullen

Mark Peairs

Kevin P Corcoran

Steve M Blonstein

David Bednash

Matin Boliek

A method and apparatus for encoding and decoding data is described. The present invention includes a method and apparatus for generating transformed signals in response to input data. In one embodiment, the transformed signals are generated using a reversible wavelet transform. The present invention also includes a method and apparatus for compressing the transformed signals into data representing a losslessly compressed version of the input data. In one embodiment, the present invention decomposes the input data using a non-minimal length reversible filter. The decomposition may be performed using multiple one-dimension filters.

Method for compression using reversible embedded wavelets

Apparatus for compression using reversible embedded wavelets

A method of generating a collaborative judgment for use in coding a symbol is described. One method includes generating multiple probability estimates for a symbol to be coded, selecting an exaggeration exponent and weighting information indicative of weighting between the probability estimates, and combining the probability estimates into the collaborative probability estimate based on an exaggeration function using the exaggeration exponent and the weighting information.

Collaborative judgement in statistical coding

A method and apparatus for decompressing and compressing data is described. The present invention provides an encoder for use in a compression system having a decoder for decoding information generated by the encoder. The encoder of the present invention includes a coder for producing codeword information in response to data. The encoder also includes a reorder unit that generates a coded data stream in response to the codeword information from the coder. The reorder unit comprises a run count reorder unit for arranging codewords into a decoding order and a bit pack unit to combine variable length codewords into fixed length interleaved words and to output the fixed length interleaved words in an order required by the decoder.

Method and apparatus for encoding and decoding data

An encoding and decoding system that includes a model implemented hardware or software that is capable of operating on arbitrary data (e.g., data of a different or variety of types.) The model generates a context and binary decision for each symbol, which a binary entropy coder that uses to generate a compressed bit stream. One context model is operable with arbitrary data and uses context bins of various orders to generate a context and a decision for each symbol in an input symbol stream. An entropy coder estimates probability and generates compressed data stream in response to contexts and decisions from the model and according to generated probability estimates.

Method and apparatus for compressing arbitrary data

Automatic detection of defective pixel locations from digital images of scanned documents is provided. A list of tentative defect locations is kept, and as each document is scanned, entries are added to the list. As subsequent documents occur with the same color pixel in the same location, a count for that tentative defect location is incremented, but if the color of the pixel in that location changes, the count is reduced or zeroed. If a count for a location is incremented above a threshold, the tentative defect is flagged as an actual defect and a defect detector outputs or flags that pixel location as being an actual defect location. If memory size is constrained, the number of entries in the defect list is capped at some maximum size and a tentative defect location is added to the list only if an entry is available. To avoid the bias of the defect list being filled with pixel locations from only the first portion of documents scanned if the maximum number of entries is much less than the number of tentative defect locations, cursors changeably identify preferred regions of a document and tentative defects are only accepted for placement on the defect list from the preferred region.

Document image processor with defect detection

Transforms such as the DCT are useful for image compression. One close relative of the DCT is preferred for its arithmetic simplicity. A method and apparatus is described whereby the image compression is done with no multiplications while still compatible with a JPEG (Joint Photographic Experts Group) Transform. Other enhancements are made to improve image quality.

Apparatus and method for compressing still images

An apparatus and method for increasing the throughput of a data processing system such as an acoustic or image compression system. An addition or subtraction of two pluralities of numbers is accomplished in parallel by combining numbers into a pair of 'doublevectors,' adding or subtracting the pair of doublevectors, and separating the resultant doublevector to provide values representative of the results of the addition or subtraction on the original plurality of numbers. Similarly, a left-shift of a plurality of numbers is accomplished by combining the numbers into a single doublevector, left-shifting the doublevector, and extracting a plurality of output values representative of the left-shifted values of the original numbers. Using additions, subtractions and shifts a linear transform such as the Generalized Chen Transform may be performed using doublevectors to provide a substantial increase in computation speed.

Apparatus and method for increasing the throughput of an acoustic or

Transforms such as the DCT are useful for image compression. One close relative of the DCT is preferred for its arithmetic simplicity. A method and apparatus is described whereby the quantization operates with speeds comparable to 16 bit transforms yet the mean squared error is comparable to that of a 32 bit transform. The factorability of the transform into a relatively rapid set of additions and a set of multiplications permits an efficient pipelined data flow wherein the addition sections of the vertical and horizontal transforms are performed by the same hardware prior to a final multiplication.

The present invention provides a method and apparatus for encoding and decoding data in parallel. The present invention provides a system for decompressing a data stream having multiple codewords. The system includes an input channel that receives the data stream. The system also includes a decoder which decodes each bit of the data stream, wherein at least two of the codewords in the data stream are decoded at the same time, such that the data stream is decoded in parallel.

Method and apparatus for parallel encoding and decoding of data

A method and apparatus for reducing the necessary size of a buffer between two cascaded decoding stages is described. The present invention includes a method and apparatus for encoding data into multiple blocks of data. The present invention also includes a method and apparatus for encoding the multiple blocks of data into multiple symbols. This encoding includes a method and apparatus for limiting the multiple symbols to a predetermined number of symbols. By limiting the symbols encoded, the buffer after the decoding stage is limited so that the size of the buffer memory to buffer decompressed data output from the decoding stage is reduced.

Method and apparatus for limiting the number of a compressed output type

The present invention provides an encoding and decoding apparatus used for the compression and expansion of data. A state machine is provided having a plurality of states. Each state has at least one transition pair. Each element of the transition pair comprises zero or more bits representative of the compact code to be output and the identification of the next state to proceed to. The transition pair reflects an output for a yes and no response associated with the probability of the data to be compacted and whether the data falls within that probability.

Method and apparatus for using finite state machines to perform channel

The invention provides an improved method and apparatus for compression of palettized images. Input symbols in an M-ary alphabet are binarized based on a context model of the input data, where the binarization is selected to provide good compression by a binary encoder. The particular binarization is determined from a reindexing table which maps each input symbol to a number of binary values. The mapping is determined from the images to be compressed, and is typically transmitted with the compressed images as overhead. The mapping is a local minimum of the bitwise entropy of the binarization. With or without reindexing the input, the symbols can be converted compressed in parallel, with the bits of the input symbols buffered and reordered as necessary to ensure that bits needed for context of a bit being decoded are available before the decompressor decodes the bit being decoded. The decompressor includes a means for performing the opposite reordering such that the output of the decompressor is the same as the input to the compressor.

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Castro Valley, CA, United States of America

James D Allen