Abstract: A visual lossless encoder for processing a video frame prior to compression by a video encoder includes a threshold unit, a filter unit, an association unit and an altering unit. The threshold unit identifies a plurality of visual perception threshold levels to be associated with the pixels of the video frame, wherein the threshold levels define contrast levels above which a human eye can distinguish a pixel from among its neighboring pixels of the frame. The filter unit divides the video frame into portions having different detail dimensions. The association unit utilizes the threshold levels and the detail dimensions to associate the pixels of the video frame into subclasses. Each subclass includes pixels related to the same detail and which generally cannot be distinguished from each other. The altering unit alters the intensity of each pixel of the video frame according to its subclass.

Abstract: A reversible Discrete Cosine Transform (DCT) is described. The reversible DCT may be part of a compressor in a system. The system may include a decompressor with a reversible inverse DCT for lossless decompression or a legacy decompressor with an inverse DCT for lossy decompression.

Abstract: A method of buffering video data in a video compression system, in which a video bit stream, compressed on the basis of an international standard, is transmitted adaptively to a state of a transmission channel under a digital communication environment where a transmission speed is very low and a bit error generation rate is very high. The video data buffering method comprises the step of performing a discrete orthogonal transform operation with respect to input video data in the unit of blocks and storing the resultant coefficients in the unit of discrete orthogonal transform components.

Abstract: The present invention relates to an apparatus and a method for encoding image data which compresses image data by a combination of one-dimensional encoding and two-dimensional encoding for a plurality of lines. The apparatus is provided with a code start line selection section which changes an encoding start line position within a range of a processing unit defined by the combination of the one-dimensional encoding and the two-dimensional encoding, an encoding section which performs encoding for each processing unit from the encoding start line position, an encoding capacity determination section which determines an encoding efficiency on the basis of the result obtained by changing the encoding start line position, and an encoding control section which selects an encoding start line position at which the maximum encoding efficiency can be achieved from the determination result of the encoding efficiency. The method is performed by this configuration.

Abstract: The present invention describes a method of and apparatus for operating upon digital data by which the digital data is partitioned into a plurality of blocks, a plurality of threads are created, such that each thread includes at least one of the plurality of blocks, and thereafter each of the threads are operated upon to obtain a plurality of compressed threads, each compressed thread including at least one compressed block of digital data. In this method, the threads are operated upon using a compression engine such that a compression algorithm repeatedly, a cyclical manner, compresses data that in a previous pass was already compressed by the compression engine. Between each of the compression passes, the then compressed data is operated upon using metadata established in the previous pass to eliminate redundancies that exist in the data compressed in the previous pass.

Abstract: The invention disclosed here is a method for an encoder to encode audiovisual information for transmission to the decoder without any prior knowledge of the computational capabilities of the decoder. A descriptor containing parameters that can be used to estimate the complexity of the decoding process is embedded in the system stream. The encoder also encodes the video information in such a manner that the decoder can choose to ignore some of the information and only decode a subset of the encoded information in order to reduce the computational requirements. This method allows more than one decoder to decode the same bitstream giving different resolutions depending on the computational capability of the decoder.

Abstract: Digital video data is encoded by using the evolving states of cellular automata. The video data is subdivided into groups of three-dimensional “video cubes”. The data is transformed via 3D filters derived from the cellular automata. The ensuing transform coefficients are encoded using a sub-band-based embedded stream technique that automatically transmits or stores the most important coefficients. Compression of the video cubes is achieved when the stream encoding/decoding is terminated after 1) a stipulated maximum bit budget is reached, or 2) when a predefined maximum error rate is attained. This invention teaches an encoding method for accelerating the transmission of video data through communications networks and storing the compressed data on digital storage media.

Abstract: Compressed image data from a code memory is separated into quantization step values, code table information and variable-length codes. The variable-length codes are each decoded into a run length, a size and an additional bit string and written into a size memory. A size conversion section converts the run length, the size and the additional bit string from the size memory based on a frequency region and a size conversion amount set in a size conversion table. A variable-length code is assigned to each converted run length/size combination, and an additional bit string is attached thereto, thereby producing a variable-length code. The variable-length codes, the quantization step values and the code table information are multiplexed together to produce compressed image data.

Abstract: In order to produce a decoded image substantially identical to an original image by processing a small amount of data, utilizing a thinning circuit (subsampler) a level of compression data obtained by extracting 9 pixels of an original image by 1 pixel is limited by a level limiting circuit by extracting 2 bits thereof from an MSB. In a local decoder, the original image is predicted based on correction data to output a predicted values thereof. Then, in an error calculator, a prediction error of the predicted values with respect to the original image is calculated. The compression data is corrected by a correcting circuit in such a manner that this prediction error becomes small.

Abstract: In a tape drive, or other storage device, used for storing computer data, both record data and record structure information such as file marks are encoded with codewords to form an encoded data stream. Of the fixed number of possible fixed-length codewords, one codeword is assigned as a root sequence for one or more longer codewords. Thus, detection of the root sequence during decoding of an encoded data stream triggers the reading of a fixed number of further bits. The further bits represent file marks and any other defined information. In the tape drive (800), the tape drive interface (810) receives record data and file mark commands. The formatter (820) encodes the record data as fixed length codewords.

Abstract: Triangle mesh compression. In one embodiment, a method first generates a dual graph from a triangle mesh. The method then generates a binary tree structure from the dual graph. In one embodiment, generation of the tree structure includes removing a node of the dual graph from a stack, adding the node to a list, and determining node connections. Upon determining that there are two connections, the method adds an edge to the structure and adds a connected-to node to the stack. Upon determining that there are three connections, the method adds a branch to the structure, and adds a first and a second connected-to node to the stack.

Abstract: Raster images are highly compressed by first reordering the data. Next the reordered data is indexed to encode any and all predicted runs and literal runs. Each piece of the present line of the raster image is compared to a previous line. If there is a match, then the present piece is a predicted run and indexed accordingly. If there is no match, then the present piece is a literal run and indexed accordingly. A predicted run can have a minimum run length of one piece, and a maximum run length of the image width in pieces divided by the number of strings. The same is true for literal runs. The index strings are then compressed using a lossless compression method such as Huffman encoding. If Huffman encoding is used, the Huffman tables are predefined and known to both the compressor and decompressor. As the compressor compressed the index strings, the Huffman tables are adapted. The decompressor is notified by the compressor when the adapted tables are to be used.

Abstract: An input image signal is coded by an encoder to be outputted as a basic code string, and the basic code string is delayed by a code-string delay circuit for a predetermined period of time to be outputted as an additional code string. The basic code string is synthesized with the additional code string by a code-string synthesizer to be outputted as an output code string. Thus, there is provided an image data coding system which can quickly restore data even if the data is lost due to error and in which the increased code amount is less than the cycle refresh and the error correction.

Abstract: This invention has as its object to attain efficient encoding/decoding even when the processing time, memory, arithmetic cost, and the like of an apparatus are limited.

Abstract: A raster/block conversion circuit 12 divides an input image from an image input unit 11 into blocks. An image characteristic determination circuit 13 calculates the image characteristic for each block, thereby determining the image type for each block. Based on the determination result of the image characteristic determination circuit 13, a switch circuit 18 adaptively switches an ADCT coding circuit 14 adopting a variable-length irreversible coding technique and an intrablock quad coding circuit 15, an intrablock binary coding circuit 16, and a block run length coding circuit 17 adopting a fixed-length irreversible coding technique.

Abstract: A reversible Discrete Cosine Transform (DCT) is described. The reversible DCT may be part of a compressor in a system. The system may include a decompressor with a reversible inverse DCT for lossless decompression or a legacy decompressor with an inverse DCT for lossy decompression.

Abstract: A preprocessor for processing sample data, particularly digital video data, to improve lossless sliding window type Lempel-Ziv compression of the data. Sliding window Lempel-Ziv compression is improved by transposing the multiple bit per pixel data samples before compression so that the relatively repetitive higher order bits of successive pixels are compressed separately from the relatively volatile lower order bits of the successive pixels. The transposition is particularly suited for bit plane configured frame buffers in that compression and decompression grouping is readily performed by the manipulation of data within the individual bit planes.

Abstract: In a method and a device for transforming a stream of digital numbers, the correlation between successive numbers is utilized in order to obtain a new stream having a very low correlation between the numbers, whereby the sequence of numbers can be coded much more efficiently from a compression point of view. The numbers are for this purpose coded with the difference between a predicted number (s′(i)) and the actual number (s(i)) taking into account that the sequence does not need to be possible to decode in reverse order. The non-reversible codes can also be applied in lossy data compression schemes. Such schemes can change in accordance with the currently available bandwidth in order to obtain a graceful degradation and optimal bandwidth usage when the compressed data stream is transmitted over a channel having a time varying bandwidth. A general method and device for reversible coding are also provided.

Abstract: System and method using a competitive process to create an optimized set of variable length bit codes to encode one, two or three dimensional data and a high speed redundant lookup table for decoding the resulting representation in real time. The encoding phase consists of multiple passes through the unencoded data to determine the overall best code set for the given data. The primitives used to encode the data may be any mix of operations that captures the redundancy of the raw data. For graphic applications, specific colors and patterns copied from previously occurring data yield sufficiently high compression ratios, but any likely candidates for high frequency occurrence may be added to the mix. The encoding algorithm will ignore any non-optimal operations and assign them no space in the code set.

Abstract: An apparatus and method for compressing data is disclosed. The apparatus and method comprise: 1) analysis of the data to identify a relationship between a plurality of data elements in the data, 2) reordering the data based on the identified relationship between the plurality of data elements, and 3) identifying common sequences in the reordered data and storing these references using a lean index. The apparatus and method of the present invention further includes reordering the data to arrange related data elements adjacent to one another, and compressing the reordered data to generate a compressed data set.

Abstract: An apparatus and a concomitant method is disclosed for encoding wavelet trees in a wavelet-based coding technique, which the use of band dependent tables to address specific bands of the wavelet tree addresses.

Abstract: A period-based method for converting digital image data for a plurality of pixels from a first bit depth to a second bit depth includes receiving an input scanline of an arbitrary length comprising digital image data for a plurality of input image pixels. Each of the input image pixels is defined at the first bit depth. The input scanline is divided into a plurality of periods each comprising digital image data for a select number of input image pixels. The period is selected so that the image data for the select number of input image pixels exactly comprises m bytes when defined at the first bit depth and exactly comprises n bytes when defined at the second bit depth, wherein m and n are different integers. For each of the periods in succession, the image data for each of the select number of input image pixels is converted from the first bit depth to the second bit depth.

Abstract: A data compression system separates input data into color planes prior to compression. If needed for legacy game consoles, compression is performed by a game cartridge transparent to the console. To minimize the number of passes required of a coder/decoder, color planes are ordered by density and the densest color plane is coded first. After the first color plane is coded, other color planes are coded, but pixels which are known to have colors from previously coded color planes are not coded. The last color plane is not coded, but is deduced from all the other color planes. Alternatively, pixel color values are represented by vectors with components thereof separately coded by subcolor planes. Also, each color plane can be coded until a threshold number of pixels are coded, and the remaining pixels coded by bit plane. The image data could be coded using pixel position information as context.

Abstract: A method of automatically compressing and decompressing a digital image that is comprised of the following steps: acquiring a digital image through an image acquisition system; generating a look-up-table (companding function) based upon noise characteristics of the image acquisition system; applying the companding function to the image; processing the image using a lossless compression algorithm; reconstructing the image using the associated decompression algorithm; and applying the inverse of the companding function to the image.

Abstract: A digital image is divided into a plurality of cells having a first sequence. A random seed is generated and used to produce two sets of pseudo-random numbers. The first set of pseudo-random numbers are used to alter the location and shape of the cells thereby creating a new set of cells that the image is divided into. A measurement is taken for each of these new cells. The second set of pseudo-random numbers creates a second sequence. Each of the new cells corresponding to the first sequence is compared to another new cell corresponding to the second sequence. This comparison is related to a threshold and yields a fingerprint. The resultant fingerprint is transmitted along with the image and the random seed. A receiver performs the same algorithm on its received image. If it produces the same fingerprint as the one it receives, it is assumed that the image has not been altered.

Abstract: The present invention discloses a coder and a coding method that raise the possibility of improving the compression ratio of multivalued image data in which one pixel consists of a plurality of bits and are accordingly effective to increase the amount of image that is stored in a recording medium with a certain capacity. The coder according to the present invention includes an obtaining unit for obtaining a predetermined amount of image data in which one pixel consists of a plurality of bits, a developing unit for developing on the virtual plane each piece of the bit data in the obtained image data, and a coding unit for performing the entropy coding on the developed bit data.

Abstract: A Two Row Buffer Image Compression (TROBIC) technique is provided that operates on 32×2 blocks of pixels and uses a block-based coding scheme to provide alternative coding modes for image blocks containing different types of image data. The TROBIC algorithm automatically evaluates the image presented to determine regions containing text, graphics, synthetic images and natural images along with determining the most effective combination of global-index coding, local-index coding, lossless coding and wavelet coding to use to guarantee the desired compression ratio and high quality. The wavelet coding technique, in addition to being part of TROBIC, may be used independently in a wide variety of compression applications. The wavelet coding technique is carried out by a simple block codec with wavelets (SBCW) that uses wavelet filters to transform 32×2 image blocks into subband coefficients organized in a tree structure.

Abstract: A method and apparatus for outputting an image in which the image is divided into plural parts which are serially processed. Each part in turn is compressed in accordance with a first compression method, the same part is selectably recompressed by a second compression method in accordance with the compression results, the method by which the part was compressed is stored, the compressed part is expanded into a memory area that is common for all parts of the image in accordance with the stored compression method, and the expanded image is output.

Abstract: This image processing apparatus comprises a plurality of coding/decoding devices performing encoding and decoding by different codes, internal memory which the each coding/decoding device shares, and a control section controlling operation of the each coding/decoding device, wherein the coding/decoding devices, internal memory and control section are integrated on one chip and encoded data are converted to the encoded data with a different form within one chip.

Abstract: A method and apparatus for performing compression and/or decompression is described. In one embodiment, the present invention comprises a system having a buffer, a wavelet transform unit, and a coder. The wavelet transform unit has an input coupled to the buffer to perform a wavelet transform on pixels stored therein and to generate coefficients at an output. The coder is coupled to the wavelet transform unit to code the transformed pixels received from the buffer.

Abstract: An encoder for compressing video data to allow for its transmission over a narrow bandwidth. The encoder comprises a multiformat video codec for real-time compression digital data and a dynamic random access memory which operates as a temporary storage device storing compressed data while the codec is compressing data. A digital signal processor adjust the data compression ratio for the codec while the codec is compressing video data. An EPROM, which is connected to the digital signal processor contains the software to run the digital signal processor. A programmable gate array operates as an interface between the codec and an external processor. The array includes a read write controller which provides a read signal to the codec to allow compressed video data to be read from the codec to a parallel to serial shift register within the array. The write control signals which allow data to be written into and shifted through the register are also generated by the read write controller.

Abstract: A dithered image compression system that converts a source image into an image that is efficiently compressed and yet preserves the visual image information of the original source image in a computer environment. A preferred embodiment of the invention removes the image data from the source image that are lost during the normal storage and halftoning stages in one step. Each pixel in the source image is compared to the threshold array values. If the value of the source image pixel is less than the corresponding threshold array pixel, then a zero is placed in that position in the dithered image array, otherwise a one is placed in the dithered image array. The dithered image array is then compared with the threshold array, thereby creating a range array where the range of each pixel is determined using the dithered image array values combined with the threshold array values.

Abstract: A digital image signal is watermarked by locally changing geometric features of the image. The watermark consists of a pseudo-random, dense subset of image pixels, e.g., a pattern of lines (20). A number of significant image pixels (21,22,23), i.e., pixels which give the highest response to a predetermined processing operation, is determined and then moved (24) to the vicinity (&dgr;) of the line pattern. As a result of this “warping”, the majority of significant image pixels (21,22) is eventually located within the vicinity of the line pattern. At the receiver end, the most significant pixels of an input image are again determined. The image is a watermarked image if a statistically high percentage lies within the vicinity of the line pattern.

Abstract: A reversible Discrete Cosine Transform (DCT) is described. The reversible DCT may be part of a compressor in a system. The system may include a decompressor with a reversible inverse DCT for lossless decompression or a legacy decompressor with an inverse DCT for lossy decompression.

Abstract: An improved binary tree and decoder are disclosed wherein all the codewords are moved to one side of a binary tree. A compressed bit stream is fed to a decoder. The decoder uses a parser, an address generator, and the binary tree to determine the codewords contained in the compressed bit stream. The decoder examines the variable length encoded bits and compares them with the binary tree at each level to determine if the codeword is complete. The parser detects the end of the codeword and generates an offset for the address generator. The address generator uses the binary tree and offset to generate a block address for each unique codeword. The block address is then used to output uncompressed data from a pattern look up table.

Abstract: A system for creating copy restrictive media is disclosed. The system comprises printing a first pattern of microdots (80) on a first set of documents and printing a second pattern of microdots (82) on a second set of documents. A first key code is associated with the first microdot pattern (80), which allows a copy machine to copy the first set of documents, and a second key code is associated with the second microdot pattern (82), which allows a copy machine to copy the second set of documents. This system allows individual copyright owner to insure that no one else is able to reproduce their copyrighted documents.

Abstract: A lossless bandwidth compression method for use in a distributed processor system for communicating graphical text data from a remote application server to a user workstation over a low bandwidth transport mechanism enables the workstation display to support the illusion that the application program is running locally rather than at the remote application server. At the application server, the graphical text data is represented by a string of glyphs, each glyph being a bit mask representing the foreground/background state of the graphical text data pixels. Each unique glyph is encoded by assigning a unique identification code (IDC). Each IDC is compared with the previous IDCs in the string and, if a match is found, the IDC is transmitted to the workstation. If a match with a prior IDC is not found, the IDC and the corresponding glyph pattern are transmitted to the workstation.

Abstract: Printing hints can be efficiently compressed in a system using hierarchical compression (HVQ) by first using HVQ to generate compressed codewords, and then adding the printing hint to the codewords to generate an intermediate form of codeword, before sending this intermediate form to a pattern matching lossless compressor for final compression. Even though the same printing hint may be applied to a number of codewords, the overall compression will be affected very little by the addition of the printing hints since the hints are identical over a large number of codewords in series.

Abstract: A compression and encoding system for bi-level image data determines the available memory capacity of a receiving device, then compresses and encodes the image data with successively increasing compression ratios until encoded data not exceeding the memory capacity of the receiving device are obtained. Preferably, the image is divided into rectangular blocks, and successive bit planes are generated on the basis of the number of dark picture elements in each block, and on the basis of adjacency relationships among like-valued picture elements in each block. Feedback may be employed to adjust the darkness of certain compressed blocks according to the darkness of the preceding block.

Abstract: A reversible Discrete Cosine Transform (DCT) is described. The reversible DCT may be part of a compressor in a system. The system may include a decompressor with a reversible inverse DCT for lossless decompression or a legacy decompressor with an inverse DCT for lossy decompression.

Abstract: A data processing scheme capable of realizing both the reduction of an amount of data due to the compression and the shortening of a time required to refer to data, as well as the lowering of the power consumption in a portable information device. A compression start position is detected, and data subsequent to the compression start position are compressed, and then a data sequence is generated from data prior to the compression start position and subsequent compressed data. In a case of reading a data sequence containing non-compressed data and subsequent compressed data, a boundary position between the non-compressed data and the compressed data is detected, and only the compressed data subsequent to the boundary position is expanded.

Abstract: A scalable encoding apparatus and method accurately performs motion vector scaling in interframe coding so that an optimal weight having the best S/N ratio is applied, eliminating the drift effect on the image and enabling good video recovery.

Abstract: A set of image feature extraction techniques to locate and group documents based upon appearance in a database management system. The system automatically determines visual characteristics of document images and collects documents together according to the relative similarity of their document images. The system is operable on both binary and grayscale images.

Abstract: A system for compressing an ASCII or similarly encoded text file creates an alphabetically ordered main dictionary listing all unique words appearing in the text file. A text file "word" is defined as a sequence of characters ending with one or more "word terminators" such as spaces, commas, periods and carriage returns. The compression system also creates a common word dictionary referencing words most often encountered in the text file. The sequence of words forming the text file is represented by a word index, a list of one byte and two byte references to common and main dictionary words, respectively. The system compresses the main dictionary using three complementary techniques. First, leading characters of each dictionary word matching leading characters of a next preceding dictionary word are represented by data indicating the number of matching characters. Second, commonly encountered dictionary word suffixes are represented by data referencing entries of a small suffix dictionary.

Abstract: The efficiency of variable-length (VL) encoding data using a defined VL encoding table is characterized and one or more changes to one or more entries of the defined VL encoding table are determined that increase the efficiency of encoding the data. An updated VL encoding table is generated from the defined VL encoding table based on the changes. VL codes for the data are generated using the updated VL encoding table, and an encoded bitstream is generated from VL codes, wherein the encoded bitstream explicitly identifies the changes. For decoding, the changes are extracted from the encoded bitstream and an updated VL decoding table is generated from a defined VL decoding table corresponding to the defined VL encoding table, based on the changes. The VL codes in the encoded bitstream are decoded using the updated VL decoding table to generate a set of decoded data.

Abstract: A method for preprocessing a binary file for data compression under a dictionary-based data compression algorithm takes advantage of redundancy in a two-dimensional binary image. The method rearranges a linear representation of a binary image, i.e. a representation based on pixels of horizontal lines, to a two-dimensional representation, i.e. a representation based on a sequence of adjoining picture areas, to achieve an improvement of compression ratio. The present invention is applicable to dictionary-based data compression methods, such as LZW, LZ77 and LZ78.

Abstract: A data compression method that uses selective encoding is disclosed. A block of data is compressed using a combination of the LZ77 and Huffman coding techniques. Each compressed block consists of a pair of Huffman code trees that describe the representation of the compressed data part and a compressed data part. Compressed data may consist of literal data that has not been detected as duplicated and length/backward pairs indicating the location of a duplicated string. Compressed data is arranged in a deflate format.

Abstract: Extended lossless imaging method and system, useful for medical and other imaging, where a succession of values of optical density or other feature of interest may be obtained by scanning an image as an array, or may be selected otherwise. Image data values in binary form are linked end to end into a concatenated number, partitionable into a set of ordered (non-repeating) numerical terms summing to it. Position counts of such a concatenated number also may be summed, as to give a "characteristic" whole part of a real number, and may be encoded arithmetically to give a "mantissa" fractional part thereof. The derived numbers are electronically stored for retrieval directly or by reverse computation, to yield reconstituted image data values, from which a lossless replica of the original image is readily made.

Abstract: The present invention aims to execute effective compression even in the case where inputted image information has the bit number smaller than that of a pixel value, such as a tag, and besides in the case where the entropy increases if a prediction error obtained by subtraction of a value of a neighboring pixel from that of an object pixel is used for calculation of the entropy.According to the present invention, in an image encoding apparatus, the inputted image information is made to be packed image data of a fixed length and provided to a couple of predicting elements and a couple of prediction error calculating elements. The packed image data and prediction errors outputted from the couple of prediction error calculating elements are provided to a prediction error selecting element and one of the data and prediction errors having a smallest entropy is selected.

Abstract: A print data processing pipeline for use in a color electrophotographic printer optimizes print quality and minimizes memory usage by separately processing lossy and lossless print data. Lossy print data may include print data or images and lossless print data may include print data for text, line art, and graphics. Partitioning print data into lossy and lossless components allows application of the print data compression operations optimized for each type of print data. High compression ratios can be achieved on lossy print data by applying visually lossless compression operations designed for the lossy print data. In addition, high compression ratios can be achieved on the lossless print data by applying lossless compression operations designed for the lossless print data. A merge unit combines the lossy and lossless print data streams after decompression to reconstruct the original image.