Abstract: A method and device for decompressing a compressed video image and capable of enlarging or contracting the image at the same time. The method utilizes an enhancement/contraction pre-processor to perform enlargement or contraction processing on the compressed data in the vertical direction. Then, at a later stage, an enhancement/contraction post-processor is used to perform enlargement or contraction processing on the decompressed data in the horizontal direction. By dividing the whole video image into a number of rows and dealing with each row sequentially, memory for storing a single row of video data is only required. Therefore, a whole image can be decompressed without using large amount of memory for storing the decompressed data; a large amount of memory is saved.

Abstract: An error detection circuit for detecting errors occurring in a data obtained by decoding a compressed image data block by block in a line length decoding system, includes a first storage device for temporarily storing the run representing the number of zeros (‘0’s) in the compressed image data and an EOB signal externally inputted, a selection signal generator for generating a first and a second selection signal in response to the EOB signal supplied from the first storage device, a first selection circuit for selectively transferring the run supplied by the first storage device or ground signal according to the first selection signal, a second selection circuit for selectively transferring the run supplied by the first storage device or ground signal according to the second selection signal, a reference value generator for generating a reference value based on the output signal of the first selection circuit according to an operation control signal externally inputted, accumulator for accumulatin

Abstract: In a picture encoding apparatus, block type determining means 22 judges whether a frame rate is lower than a threshold value A, and compares a block moving amount with a threshold value B when the frame rate is lower than the threshold value A. If the block moving amount is larger than the threshold value B, the current block is determined as a block to be compressed in a high picture-quality mode. Further, the differential value between the current block and a reference block is calculated, and the value of the high frequency component of the differential block is compared with a threshold value C. If it is larger than the threshold value C, the block is judged as a block to be compressed in the high picture-quality mode. Data amount assignment means 23 generates a quantization scale factor to assign a data amount to each block in accordance with the block type determined by the block type determining means 22, and then supplies the quantization scale factor to quantizing means 24.

Abstract: A method for encoding digital information to be transmitted from a first device to a second device, wherein the digital information is mapped according to a map of n rows and m columns which define a plurality of cells (n×m) and wherein each of said cells has a pixel value. The method is useful for compressing bitmapped images to be rendered by the simplest of graphics engines, Thus the method is particularly suited to the transmission of images to a relatively slow client on which the images are to be rendered in real time and on which any complex decompression would be too costly for such rendering. Raw compression ratios are comparable to those obtained with standard run-length encoding, but the number of drawing primitive calls required to render the compressed images directly is substantially less.

Abstract: By combining a plurality of encoding methods actively, an encoding efficiency is enhanced. The first encoder encodes a result of determination whether a prediction error is zero or not. The second encoder encodes the prediction error unless the prediction error is zero. The third encoder encodes the prediction error regardless of whether the prediction error is zero or not. The mode determinator determines the encoding mode, and the encoding controller selectively operates the first encoder, the second encoder, and the third encoder according to the encoding mode determined.

Abstract: An image processing apparatus includes an input device for inputting image data, a coder for variable-length-coding the image data input by the input device, and an adder for adding sync information as to the location of an image sync signal in the image data to the variable-length-coded image data. The invention also relates to an image processing apparatus for reproducing variable-length-coded image data with which sync information indicating the location of the image sync signal of the image data is transmitted. The apparatus includes a decoder for decoding the variable-length-coded image data, a detector for detecting the sync information indicating the location of an image sync signal, and an output device for outputting the image data decoded by the decoder in accordance with an output from the detector.

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: An image data encoding apparatus performs a two-step process to expand and compress digital image data. The apparatus includes a transform unit for performing orthogonal transform of the image data in a block-by-block manner and generating transform coefficient data. In the first step of the encoding step, a quantizer quantizes the transform coefficient data using a first quantization coefficient to generate first code data. A coefficient operation unit receives the first code data and computes a second quantization coefficient for determining an optimal compression rate of the image data. In the second step of the encoding process, the quantizer receives the second quantization coefficient and quantizes the transform coefficient data to generate second code data. The transform coefficient data is stored in a memory. By optimally compressing the image data, a high image data compression rate is achieved, which allows a greater number of compressed images to be stored.

Abstract: Multiplications in an inverse quantization portion (202) are limited to only multiplications of an effective coefficient (NZ) by a quantization coefficient (Qi) corresponding thereto. An inverse zigzag transform is performed such that fixed values "0", the number of which corresponds to a block of Huffman codes, are previously arranged and the effective coefficient (NZ) is then overwritten in corresponding positions, rather than arranging data including the fixed values "0" and the effective coefficient (NZ). Thus, multiplications of ineffective coefficients are not required and the Huffman codes are decoded at a high speed.

Abstract: Provided is a probabilistic statistical data compression/restoration method for variable-length encoding a source character and restoring a variable-length code to a character using the probability of occurrence of the source character which appears following a character string (context) of n characters which immediately precede the source character. When variable-length encoding is performed, a context registration unit successively registers context based upon an entered character without fixing the length (degree) of context, and a compressing encoder selects registered context satisfying a predetermined condition, e.g., registered context for which the frequency of occurrence is greater than a fixed value, as context (encoding context) used in encoding, and variable-length encodes a source character by using this encoding context. A restoration unit restores a code to a character by executing processing which is the reverse of the processing executed by the compressing encoder.

Abstract: A method improves the efficiency of a compression technique by introducing a new parameter to be associated with a given probability range for events. When the new parameter is to be utilized, that parameter is associated with a table that matches codes to sequences of events. The coder receives the bit stream, detects a sequence of events and then reads the corresponding code from the table when the coder recognizes that the probability range with respect to the code corresponds to this new parameter. At the decoder the received bit stream is matched to table entries to determine the corresponding event sequence.

Abstract: An image processing apparatus entropy encodes plural encoding target data by using a first entropy encoding table to provide respective data amounts of plural encoded data and compares the data amounts of plural encoded data with each other. One of the plural encoding target data is selected according to the result of the comparison and a second entropy encoding table is produced according to the content of the selected encoding target data. The apparatus then entropy encodes the selected encoding target data utilizing the second entropy encoding table.

Abstract: A picture encoding device for compressing picture data using the Huffman encoding system includes a grouping portion for recognizing a group to which an AC coefficient belongs, and a data processing unit receiving a run-length, a group number, and an additional bit, which are output from the grouping portion, for recognizing a ZRL* code and an effective coefficient. If the run-length group number (N/S) is an effective symbol, i.e., not a ZRL* code, the data processing unit transmits the effective symbol to a Huffman encoding portion in the next stage. If the N/S comprises a ZRL* code, a ZRL* code count detection counter is incremented. If an EOB* code follows a ZRL* code, ZRL* codes are deleted in a number corresponding to the count value from the ZRL* code count detection counter. The picture encoding device effectively carries out Huffman encoding without encoding unnecessary ZRL* codes in a Huffman encoding system.

Abstract: An image stored in a memory of a computer as pixels, each pixel including a bit pattern to indicate a grey-scale level. The image is compressed by grouping the pixels of the image into a plurality of regularized groups of pixels. The partitioning of the image can be in groups of four by four adjacent pixels. Groups of pixels having identical bit patterns are identified. The groups of pixels are encoded according to a frequency of groups of pixels having identical bit patterns.

Abstract: A method and apparatus for reducing power consumption and system bus load caused by a display controller in a unified memory system. A compression engine monitors a bus over which display data from the unified memory flows. The compression engine captures and compresses a copy of the display data corresponding to a display frame. The compressed data is stored in a small memory unit. Subsequent refreshes of the display are serviced by a decompression engine. The decompression engine decompresses the compressed data from the small memory unit and provides the decompressed data to the display controller.

Abstract: Method of reinitializing dictionaries in a data transmission system using data compression having a transmit device and a receive device, and in which strings of characters have to be transmitted in a compressed form, the transmit device having a transmit dictionary storing codewords associated with the strings of characters which are transmitted instead of the strings of characters, the receive device having a receive dictionary storing codewords associated with the strings of characters, and both dictionaries being updated each time a new string of characters has to be transmitted so that the contents of the dictionaries remain identical.

Abstract: Given run length codes are decoded and continuity between a run currently being processed and a previously processed run is determined. Then, the same label as that of said previously processed run is designated to a said run currently being processed if it is determined that they are continuous with one another. A link is formed between a plurality of previously processed runs if it is determined that said run currently being processed is continuous with each of the plurality of previously processed runs, thus labels of the plurality of previously processed runs being integrated together. If MR or MMR codes are used, the run length codes include information concerning relationship between color-changing pixels situated on an immediately preceding decoded scan line and color-changing pixels situated on a scan line currently being decoded which is located immediately below the immediately preceding decoded scan line.

Abstract: A run length encoder for encoding DCT coefficients obtained in a DCT, a quantization, and a scanning steps in block units to output an encoded (run, level) symbol, and outputting a predetermined (run, level) symbol if the obtained DCT coefficients of the block unit are all zero, comprises a run length encoding core for receiving the DCT coefficients and outputting the (run, level) symbol; a zero coefficient detector for detecting whether the DCT coefficients are `0` or not; a zero block detector for receiving an output from the zero coefficient detector to detect whether all of the DCT coefficients of each block are `0` or not; and an output selector for selecting the 2-dimensional symbol outputted from the run length encoding core to output a (run, level) symbol or a predetermined (run, level) symbol, if the block determined in the zero block detector is non-zero or zero block, respectively.

Abstract: In an electronic still camera, a compression coefficient estimating unit performs preencoding using only an LA component of FBTC compressed data read from an image memory, and estimates an optimal compression ratio based on the result of preencoding. Thereafter, JPEG encoder performs JPEG compression on the image data applied from FBTC decoder with the estimated compression coefficient, and transfers the result to a recording apparatus. As compared with the prior art in which image data is directly preencoded, the time for preencoding can be significantly reduced and image memory requires smaller capacity.

Abstract: An image data compression/expansion system capable of compressing/expanding image data at a high speed and less costs is provided. The system includes an image data compression device provided with an extraction circuit for extracting, from pixel information of an image composed of pixels, characteristic data each representing a characteristic value, such as a luminance and a color difference of a pixel, which is of significance for the image, and a position data of such a significant pixel, and includes an image data expansion device which interpolatingly forms characteristic data of all the pixels of the image from the characteristic and position data of the significant pixels.

Abstract: First-pass processing is applied to a video sequence comprising a plurality of video frames to generate first-pass processing results for the video sequence. After completing the first-pass processing, subsequent-pass processing is applied to the video sequence using the first-pass processing results to generate subsequent-pass processing results. An encoded bitstream is generated for the video sequence based on the subsequent-pass processing results.

Abstract: A multi-standard video decompression apparatus has a plurality of stages interconnected by a two-wire interface arranged as a pipeline processing machine. Control tokens and DATA Tokens pass over the single two-wire interface for carrying both control and data in token format. A token decode circuit is positioned in certain of the stages for recognizing certain of the tokens as control tokens pertinent to that stage and for passing unrecognized control tokens along the pipeline. Reconfiguration processing circuits are positioned in selected stages and are responsive to a recognized control token for reconfiguring such stage to handle an identified DATA Token. A wide variety of unique supporting subsystem circuitry and processing techniques are disclosed for implementing the system.

Abstract: A pixel which is one pixel prior to a pixel to be coded x in image data is defined as a specific pixel a, and differences (b-a) and (c-a) between each of pixel data of neighboring pixels b and c and pixel data of the specific pixel a are calculated. The differences (b-a) and (c-a) are compared to a predetermined value Th1, and if both of the differences (b-a) and (c-a) are less than the predetermined value Th1, a difference (x-a) between pixel data of the pixel to be coded and the pixel data of the specific pixel is encoded by Markov model coding on the basis of the difference (x-a) and the differences (b-a) and (c-a). Whereas, if at least one of the differences (b-a) and (c-a) is not less than the predetermined value Th1, then the pixel to be coded is encoded by predictive coding on the basis of an average of the pixel data of the specific pixel a and the neighboring pixel b, {(a+b)/2} and an error of the average with respect to the actual pixel data of the pixel to be coded x.

Abstract: The digital information encoding apparatus comprises a context generation means for extracting a reference picture element from an inputted picture data, a context storage means for temporarily storing said context, a context table storage means comprising a read address input node, a read/write context table storing portion, a data output node, a write address input node and a data input node, a probability estimating table storage means comprising an address input node for receiving a probability estimation index in a probability estimating data, and a data output node which outputs a probability estimating data, and an arithmetic calculation means for receiving a picture data to be encoded and for outputting a renewal data including both the prediction symbol and the probability estimation index to said context table storage means.

Abstract: The invention is a process and apparatus for estimating a bit budget in a circuit for compressing digital data, especially digitized television signals. Signals represented by N-bit coded samples, are estimated based upon the probability of a bit of given order having a given value (0 or 1) out of M binary words representing M samples of the signal. An entropy calculation is performed on the basis of the probabilities corresponding to the N bits with the sum of all the entropies corresponding to the desired estimate.

Abstract: There is provided a high speed variable length coding system having a small hardware scale.

Abstract: A signature capture device includes a CPU that executes a routine to losslessly compress signature data in realtime such that decompression recovers a legally acceptable replica of the original signature. Digital data representing the pixel start point of a signature run is stored in preferably 10-bit or 9-bit format, and is then reduced to a common lower format of 9-bit or 8-bits. Subsequent data points within a run are reduced to the same common lower format and are compared to the common lower format version of the start point data. The differential between the start point and the adjacent second point is calculated and encoded with 4-bits if possible, or with 8-bits otherwise. The differential between the third point and second point is calculated and encoded with 4-bits or 8-bits, as required, and so on, within the run. A run is initiated by a pen-down status, or if a present run exceeds a predetermined length, or if a differential can no longer be encoded with 4-bits and requires 8-bit encoding.

Abstract: An image processing device which processes a portion of the decompression process including a lot of comparatively complex operations like an inverse discrete cosine transform by software with using a high-performance, general-purpose processor capable of parallel processing, and the other portion of the decompression process which is comparatively simple but requires frequent access to a memory, e.g., when other frame data is to be read out for processing of encoded interframe predictive image data, or is comparatively simple but substantially hard to process in parallel, e.g., when variable length coded pixel values are to be decoded, by hardware with the use of a specialized peripheral circuit.

Abstract: A method and apparatus for decoding variable length code (VLC) data employ a hybrid technique of parsing short-length VLC codes using a binary tree or binary search procedure and parsing longer VLC codes using a table lookup procedure. This technique includes the steps of accessing a plurality of bits of coded bitstream data, bit testing a preselected number N first bits of the plurality of bitstream bits and determining whether the N first bits include a complete VLC code. If the N first bits include a complete VLC code, a VLC code is decoded in accordance with a result of the bit testing step. If the N first bits do not include a complete VLC code, a VLC code is decoded from a lookup table to a table element addressed by the bits of coded bitstream data.

Abstract: In an Hadamard transform coefficient predictor for 8-point and/or 8.times.8-point Hadamard transform, when the transform coefficients of one-dimensional 8-point Hadamard transform are represented by y(0), y(1), . . . , y(7) from the lowest order, y(1) is multiplied by 1/2 and output as a prediction value of y(3), y(2) is multiplied by 1/4 and output as a prediction value of y(4), y(2) is multiplied by 1/2 and output as a prediction value of y(6), and y(1) is multiplied by 1/4 and output as a prediction value of y(7). Alternatively, when a and b represent real numbers which are above zero and below 1, the multiplication value of y(2) and b/2 and the multiplication value of y(4) and (2-2b) are added to each other, and the addition result is output as a prediction value of y(6). Further, the multiplication value of y(1) and a/4 and the multiplication value of y(3) and (1-a)/2 are added and the addition result is output as a prediction value of y(7).

Abstract: An image compression scheme is disclosed which models the human visual perception system. Using quantization of image error values, according to a visually-lossless scheme, an image can be compressed such that it is visually indistinguishable to the naked eye from the original image. To aid in image compression on portable devices such as a digital camera, the quantization can be precoupled into a look-up table.

Abstract: An advanced video compression coding system which employs variable block size transforms to improve the compression efficiency for transmission of video pictures. A picture block segmentation map is transmitted as a one-dimensional series of block-size codes by scanning the segmentation map in accordance with a predetermined scanning pattern and on the basis of block size. A block-size code is skipped when the scanning pattern intersects a block which has already been scanned earlier. The series of block-size codes is then run-length and Huffman-coded before being transmitted.

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 method for compression and decompression of dithered images is disclosed. Logical units (tiles) of the binary representation are classified into equivalence classes which are then compressed. Each equivalence class represents tiles having similar gray levels (i.e. the same number of black pixels), but which may have different sequences of black and white pixels. Each equivalence class has associated with it a predefined set of rendering exemplars. Each of the exemplars has a similar gray level. Upon decompression, each instance of an equivalence class takes on the value of one of the rendering exemplars which is selected pseudo-randomly.

Abstract: A microblock-level partitioned digital HDTV video decoder for decoding a bit stream consisting of a series of macroblocks of digital video data which are coded in accordance with an MPEG or other predetermined digital compression code. The decoder includes a bit stream parser for identifying boundaries between the macroblocks and producing macroblock boundary information indicative of the identified boundaries, a bit stream formatter for combining the macroblock boundary information with the bit stream to produce a combined bit stream having successive multi-bit portions, a rate buffer for storing and sequentially outputting the successive multi-bit portions, first and second FIFO memories, and a FIFO controller for alternately write enabling the first and second FIFO memories in response to the macroblock boundary information. The FIFO memories thereby alternately store the successive macroblocks in the combined bit stream sequentially outputted from the rate buffer.

Abstract: A data processing system (10) is disclosed which comprises a microprocessor host (12) coupled to a decoding system (14). A host interface block (18) receives a bit stream and passes bit stream on to a system decoder block (20). The system decoder block (20) extracts the appropriate data from the bit stream and loads an input buffer (24) or an optional external buffer (26). An audio decoder block (28) retrieves the data from the input buffer (24) and generates scale factor indices, bit per code word values and subband samples which are stored in an arithmetic unit buffer (30). A hardware filter arithmetic unit block (32) retrieves the information from the arithmetic unit buffer (30) and dequantizes, transforms and filters the data to generate PCM output data which is loaded into a PCM buffer (34). The data within the PCM buffer (34) is output by a PCM output block (36) to a digital-to-analog converter (16).

Abstract: An image information coding apparatus includes a block generator for dividing image information into pixel blocks, each of which consists of a predetermined number of pixels. A block selector selects a pixel block in a position different from that of a pixel block selected in a preceding block line in a main scanning direction from the pixel blocks generated by the block generator. A parameter setting device sets a coding parameter to a predetermined value. A first variable-length coding device conducts variable-length coding of the pixel block selected by the block selector using the coding parameter. A code amount controller changes a value of the coding parameter so that the code amount of the pixel block selected by the block selector and coded by the first variable-length coding device is not more than a predetermined code amount, and a second variable-length coding device conducts variable-length coding of all of the pixel blocks using a coding parameter changed by the code amount controller.

Abstract: Image data of one frame stored in a memory is repetitively read a plurality of times as a still image. The read image data is encoded and recorded. In this case, the image data of one frame is divided into a plurality of areas, and the image data is encoded so as to make the image quality of the image data at a particular area be better than that of the image data at the other areas. The particular area in each set of the image data repetitively read is disposed differently. A still image of high quality can be therefore obtained.

Abstract: A digitized image is divided into blocks and a wavelet transform is performed, producing wavelet blocks which are quantized, scanned into linear sequences, and then coded. The scanning of each wavelet block starts with a purely low-frequency element. The high-frequency elements are scanned in a sequence that depends on the occurrence of non-zero elements among the high-frequency elements. When a non-zero element is scanned, this information is used to proceed quickly to related high-frequency elements. This scanning method tends to produce a linear sequence in which non-zero elements are clustered together. Such sequences can be coded efficiently.

Abstract: The present invention relates to an image data reconstructing appatatus for reconstructing an original image by dividing image data into a plurality of blocks each comprising NXN picture elements, performing two-dimensional orthogonal transform on each of said blocks, quantizing and encoding the result of said transform, decoding the encoded result, dequantizing and two-dimensional inverse orthogonal transforming the above result, wherein an operation associated with the multiplication is skipped if a multiplication by zero is detected when two-dimensional inverse orthogonal transform is performed. Before performing dequantization, two block volume of buffer is provided before or after performing two-dimensional inverse orthogonal transform for executing a pipeline process.

Abstract: In a variable length code processor or image processor for encoding data to be coded into a variable length code corresponding to its run length and level, and decoding a variable length code to be decoded into a corresponding run length and level, there are provided a first memory for storing a variable length coding table which outputs a variable length code using its run length and level as input, a first shifter which applies a bit shift to the variable length code output by the first memory based on its length, a second memory for storing a variable length decoding table which outputs a run length and level using a variable length code as input, and a second shifter which applies a bit shift to the variable length code to be decoded based on the length of the variable length code decoded on the immediately preceding occasion, and supplies it to the second memory as input.

Abstract: An image signal processor and an image signal processing method arranged to limit a deterioration in image quality at the time of compression and expansion at a low coding rate. Data of an input image undergoes pre-processing in a pre-processing unit before being compressed by a compressor unit in accordance with the MPEG method. An information amount prediction processor calculates activity representing the complexity of the image input through an image input unit, and sets filter coefficients and the number of pixels of an output image according to the activity such that the amount of information of a picture to be compressed is reduced. The information amount prediction processor supplies a filter processor and a thinning-out processor with the filter coefficients and the number of pixels, respectively. The filter processor performs filtering with the filter coefficients, and the thinning-out processor converts the input image so that the output image has the set number of pixels.

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 method and an apparatus for compressing and decompressing data employ a splay coding instead of an arithmetic coding to achieve a high speed code entering process. The data compressing apparatus encoding input data according to a history of occurrence of the input data in the past to compress it, includes a pre-data retaining unit retaining a context, a history retaining unit retaining a combination of input data and a context, a code tree retaining unit retaining code trees each independent for each context, a code tree determining unit determining a code tree, a code outputting unit outputting unique data according to bifurcation from a node on the code tree, a code tree rearrangement unit exchanging an encoded leaf with another leaf or an internal node, and a pre-data updating unit entering the data in the pre-data retaining unit.

Abstract: The invention provides a picture data decompression apparatus which reduces the time required for decompression of picture data and operates at a high speed. The picture data decompression apparatus includes a module switching section for extracting code patterns in units of n bits the compressed picture data, m decoding and dequantization modules, and an inverse orthogonal transform section for inverse orthogonal transforming decoded and dequantized data from the m decoding and dequantization means. Each of the decoding and dequantization modules decodes and dequantizes, from a code pattern in units of n bits extracted by the module switching section, only a predetermined variable length code of a single unique code pattern of n bits from among m different predetermined patterns.

Abstract: Conventionally, when compressing data, since data (words) are sequentially retrieved from the head of a dictionary, a large amount of time is required for compression processing. Particularly when compression/expansion processing is performed a plurality of times, a large amount of processing time is required. In order to solve such problems, input data is dealt with as a set of words having a specific number of bytes, and a word retrieval table having a size equal to or larger than the size of a dictionary for registering words is provided. By storing the position of each word registered in the dictionary in the word retrieval table, it is unnecessary to sequentially retrieve data (a word) from the head of the dictionary, so that compression/expansion processing can be promptly performed.

Abstract: A method and apparatus for reducing power consumption and system bus load caused by a display controller in a unified memory system. A compression engine monitors a bus over which display data from the unified memory flows. The compression engine captures and compresses a copy of the display data corresponding to a display frame. The compressed data is stored in a small memory unit. Subsequent refreshes of the display are serviced by a decompression engine. The decompression engine decompresses the compressed data from the small memory unit and provides the decompressed data to the display controller.

Abstract: Image signals are encoded following a spatial decomposition pattern that is based on a selected location within the image. The resulting sequence of sets of encoded image signals may be transmitted to a remote node for decoding and display. The display of the decoded signals is progressively updated as subsequent sets of encoded image signals are received and decoded. In a preferred embodiment, the first set of encoded image signals comprises DC transformed signals corresponding to the original image, while the subsequent sets of encoded signals comprise AC transformed signals corresponding to the original image.

Abstract: An image coding apparatus which includes a first means for fixing or limiting quantity of code produced by compressively coding a given image data, independent of the image, a second means for conducting variable length compression of which quantity of code produced varies according to the image, and a selection means for selecting the first and second means.