Abstract: In a digital coding apparatus or a digital coding and decoding apparatus for image data compression and expansion by means of Huffman coding, a Huffman coding circuit converts a combination of ZERO RUN and VALUE into a variable-length code. A code length calculation circuit has an AC code length table for prestoring variable-length codes and their code lengths in corresponding relationship. The code length calculation circuit inputs not a ZERORUN-VALUE combination but a variable-length code from the Huffman coding circuit, thereby calculating from the variable-length code inputted its code length according to the AC code length table. The present invention can provide a downsized AC code length table in comparison with a conventional one that stores ZERORUN-VALUE combinations and code lengths in corresponding relationship.

Abstract: A method of enhancing a digital image that was transmitted with a reduced amount of digital data representing the digital image in which the differences between pixels in the digital image before compression are compared to corresponding pixels in a compressed version of the digital image and in which a statistical distribution of the differences is evaluated to determine which of the differences should be corrected. A receiver identifies portions of a received digital image that are to be enhanced, and a transmitter forms an error image for the identified portions. The amount of digital data in the error image may be reduced by selecting for transmission parts of the error image in which the amount of digital data that is needed to enhance the received digital image is less than a predetermined number of bits, the predetermined number of bits being selected from the distribution of the differences so as to enhance at least a predetermined percentage of the received digital image.

Abstract: The present invention relates to an image data reconstructing apparatus 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: A system for processing a stream of digital bit sets, each related to a different subject in a passing array, and including an arrangement for compressing the bit-sets and sending the results to an utilization stage; plus: a preprocessing stage for distributing each bit set in N parallel bit-compression paths, with all input sent to a common input buffer feeding these paths and each compression path being adapted to execute a prescribed first compression to ascertain "initial factors", and then a prescribed second compression to use the initial factors, with the second compression values selected according to "word count" factors derived from results of the first compression, and to thus provide a prescribed time-compressed output to the utilization stage; with both compressions performed according to JPEG standards; and the second compressions performed using prescribed selected QM and Huffman table values, and with a post processor stage to accept the compressed; data as 32-bit output and funnel it down to

Abstract: A novel method of improving the motion estimation and coding efficiency of Interframes in a video compression system is disclosed. The method teaches a novel minimization function to be used to determine the optimum motion vector for a block within a picture. The minization function takes into account not just the conventional sum of the differences but also the quantization step, the motion vector itself and the predicted motion vector. The minimization function disclosed better balances the tradeoff between the size of the motion vectors and the size of the resulting residuals. The results are particularly useful when the range of the search is increased. Motion vectors closer to the prediction motion vector will be favored over better matches found further away from the prediction motion vector. In addition, a novel variable length coding (VLC) method is also disclosed.

Abstract: Selecting a Huffman table to encode a set of signals, such as video signals, from a set of predefined Huffman tables. A histogram is generated for the set of signals and used to determine the number of bits to encode the set of signals for each of the predefined Huffman tables. The Huffman table that provides the smallest number of bits to encode is selected for encoding the set of signals into the encoded bitstream. In a preferred embodiment, a dynamic Huffman table is also generated for the set of signals and used to estimate the number of bits to encode the set of signals including the number of bits to encode the dynamic Huffman table. If using the dynamic Huffman table results in fewer bits in the encoded bitstream, then the dynamic Huffman table is used (and explicitly encoded in the bitstream) instead of the selected predefined Huffman table.

Abstract: Picture signal encoding and decoding apparatus capable of realizing a satisfactory operation in encoding and decoding a picture image at a stable speed without being restricted to the upper limits of input and output speeds in a transfer path or a storage device for encoded data. In a picture signal encoding apparatus comprising a block divider, an orthogonal transformer, a quantizer and a variable length encoder, there are further included a band divider for dividing quantized coefficients into a plurality of mutually prime subsets, a plurality of variable length encoders for encoding the quantized coefficients of each subset to obtain encoded data of each subset, and a plurality of memories or transferrers for storing or transferring the encoded data of each subset individually.

Abstract: In a method for storing and playback of a repertoire of fixed videotexts, in which the videotext is stored by characters in digital form in an electrical memory, the quantity of the data to be stored can be effectively reduced in that in addition to the characters, position characters are stored and that for recurring, identical character sequences of greater length, instead of the character sequence, a reference to the location of the already stored character sequence is stored. The playback of the thus compressed texts can take place without problems in real time, i.e., without noticeable delay.

Abstract: An ADCT mode or a standard mode of still image encoding is employed to perform fixed length encoding.According to the present invention, an image processing apparatus includes a circuit for counting code lengths, a circuit for cutting off encoding of a block (appending an end of block (EOB) code at an earlier step). Therefore, when an average code length is longer than a predetermined value, EOB is allocated in the middle of encoding of a block. Thus, code lengths are controlled.

Abstract: A data compression method utilizing a series of rules which are chosen for best compressing selected data. Rules are provided for converting each datum into a binary value, and encoding this binary value into a variable-width bit field. Rules are provided for automatically increasing or decreasing the binary field width which encodes the next data value, based on the current field width and encoded data value. An escape code is used to increase the field width for the next encoded value. A rule for efficient run-length encoding of repeated values or codes may also be included.

Abstract: Plurality of encoding methods and apparatus for encoding video data in a manner that makes it well suited for decoding by either regular or downconverting decoders are described. In one embodiment, the selection and/or generation of motion vectors by an encoder is controlled so that only motion vectors having a size that corresponds to an integer multiple of a downsampling rate expected to be used by a downconverting decoder are generated and/or selected. In another embodiment, motion vectors having a size which corresponds to an integer multiple of an expected downsampling rate are preferred over other motion vectors. In various additional encoder embodiments feedback circuitry which models a downconverting decoder, and/or which provides feedback information on downconverted images generated by decoding the compressed video data generated by the encoder using a downconverting decoder, are incorporated into the encoder of the present invention.

Abstract: A memory interfacing method for a variable-length decoder and a circuit therefor are provided. The memory interfacing circuit includes a read controller for generating a read chip-enable signal and a read address in response to a first request signal output from the variable-length decoder, generating a second request signal when the read address reaches a predetermined level, and providing the second request signal to an external memory controller which is connected to an external memory, a write controller for generating a write address and a write section signal in response to an accept signal generated by the external memory controller in response to the second request signal, and an internal memory controller which includes an internal memory, for controlling data provided from an external memory to be written according to the write address and the write section signal generated by the write controller.

Abstract: A variable length coder is disclosed having a zig-zag memory for continuously receiving blocks of coefficients while outputting the coefficients in zig-zag scan order. The zig-zag memory has a first memory for writing each odd ordinalled block therein according to a zig-zag scan as the odd ordinalled block is inputted. The first memory subsequently reads-out each of the zig-zag scanned odd ordinalled blocks while the zig-zag memory receives each even ordinalled block. The zig-zag memory also has a second memory for writing each even ordinalled block therein according to a zig-zag scan as the even ordinalled block is inputted. The second memory subsequently reads-out each of the zig-zag scanned ordinalled blocks while the zig-zag memory receives each odd ordinalled block. The zig-zag memory further includes a read counter which generates addresses and selectively outputs the addresses to the first memory for reading out each odd ordinalled block, while the zig-zag memory receives an even ordinalled block.

Abstract: Data items associated with different locations in a spatial field of locations are written in a memory. The memory comprises a length memory in which for each location there is stored a length code which indicates the memory length required for the data item. For the reading of a data item associated with a location, the address of the data item is calculated by reading the length codes for the data items of preceding locations from the memory and by summing the lengths indicated.

Abstract: An image signal compressing device has a quantization processing circuit in which DCT coefficients are quantized using a quantization table, and thus, quantized DCT coefficients are obtained. In a Huffman table selection unit, a Huffman table is generated in accordance with a Huffman code length table, which is determined in accordance with the minimum value of the quantization coefficients forming the quantization table. In a Huffman encoding process circuit, the quantized DCT coefficients are Huffman-encoded. The maximum value of the table number of the Huffman code length table is small, as the minimum value of the quantization coefficient is large.

Abstract: In this image coding method and apparatus, an image is divided into a plurality of areas. Information indicative of the image is variable length coded into data of, for instance (138.times.132) symbols. Boundary information corresponding to the area is transmitted after the data for each 128 symbols, after being variable length coded.

Abstract: A pixel block is coded by both of a quadrature transform coding section and a block truncation coding section. A code amount counter determines a first code amount of one-block coded data produced by the quadrature transform coding section. A code amount judgment section compares the first code amount with a threshold that is smaller than or equal to a second code amount of one-block coded data produced by the block truncation coding section, and produces discrimination information indicating a comparison result. A selector selects the coded data that is output from the quadrature transform coding section if the first code amount is smaller than the threshold, and selects the coded data that is output from the block truncation coding section if the first code amount is larger than the threshold. A storage section stores the discrimination information for each pixel block and the coded data that is output from the selector and corresponds to the discrimination information.

Abstract: In a modified Huffman (MH) code decoding apparatus, an MH code is composed of a first part and second part. The apparatus includes a code conversion table for outputting a run data in response to an index data and a code length table. The index data is composed of a color data indicative of a color of a run corresponding to the current MH code, a first code length data associated with a length of the first part of the current MH code, and a second part data indicative of the second part of the current MH code. The run data is composed of the color data, a code type data indicative of whether the current MH code is a terminate code or a make-up code, and a run length data indicative of a length of the run.

Abstract: In a code compressing system for determining a quantizing step of a image compressing code, a second DCT calculating portion performs a DCT calculation for each element reduced and divided by a picture dividing portion. A second quantizing portion quantizes the calculated result with the maximum value of quantizing steps of an applicable system. A third quantizing portion quantizes the calculated result with the minimum value of the quantizing steps of the applicable system. A code amount controlling portion determines the difference between the code amounts generated by the second quantizing portion and the third quantizing portion for each element divided by the picture dividing portion and obtains an optimum quantizing step corresponding to the determined result, the target compressing ratio, and the target encoding bit rate. A first quantizing portion quantizes the calculated result of a first DCT calculating portion with the optimum quantizing step determined by the code amount controlling portion.

Abstract: An adaptive variable-length coding/decoding method performs an optimal variable-length coding and decoding depending on an intra mode/inter mode condition, quantization step size and a current zigzag scanning position, such that a plurality of variable-length coding tables having different patterns of a regular region and an escape region according to statistical characteristics of the run level data are set. One of the variable-length coding tables is selected according to mode, quantization step size and scanning position, and the orthogonal transform coefficients according to the selected variable-length coding table are variable-length-coded.

Abstract: A computer-implemented method for encoding symbols of a current message with a variable-length code. According to a preferred embodiment, the statistics of the current message, are analyzed, wherein the symbols of the current message constitute a symbol set. Dominant symbols of the symbol set which are out of order are determined. Selected symbols of the dominant symbols are reordered in the variable-length code to reduce the size of code words of the variable-length code which represent the selected symbols.

Abstract: Disclosed are an image coding method and apparatus for coding digital image data in a highly efficient manner, and to an image decoding method and apparatus for decoding the data thus coded. Each image signal constituting the image data is partitioned into a plurality of pixel blocks, and coding of each of the image signals is performed in block units. A plurality of items of coded data obtained by such coding are gathered together to form a block (a re-sync block) corresponding to each image signal. A plurality of the re-sync blocks corresponding to the image signals of an image area of the original image data are sequentially combined, boundary-line information is inserted between mutually adjacent re-sync blocks, and an error correction code is attached to form a code for transmission. In the apparatus for receiving this code, the code is decoded into the original image data by partitioning the code into re-sync blocks and performing decoding and interpolation in re-sync block units.

Abstract: A DCT VLC decoding method substantially lessens the computational burden of picture dequantization. The method of decoding variable length code (VLC) data includes the step of receiving a bitstream sequence organized into a hierarchy of levels including, in order, a sequence layer, a group of pictures layer, a picture layer, a slice layer, a macroblock layer, and a block layer. In the sequence layer, the method defines a quantization matrix. In a macroblock layer, the method defines a quantizer scale parameter in the macroblock layer, multiplies the quantization matrix times the quantizer scale parameter and stores the product in a quantization multiplication factor. In the block layer, the method parses an encoded data bitstream to detect a VLC code in the block layer and dequantizes the VLC code by multiplying the VLC code times the quantization multiplication factor.

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. The apparatus includes a Huffman decoder for decoding data words encoded according to the Huffman coding provisions of either H.261, JPEG or MPEG standards. Data words in the tokens include an identifier that identifies the Huffman code standard under which the data words were coded. The Huffman decoder responds to the identifier and converts the received data words to JPEG Huffman coded data words. An index number into a lookup table is associated with each JPEG Huffman coded data word, and a decoded data word is generated corresponding to the index number.

Abstract: MPEG compressed data is decompressed in a computer system by sharing computational decompression tasks between the computer system host microprocessor, the graphics accelerator, and a dedicated MPEG processor in order to make best use of resources in the computer system. Thus the dedicated MPEG processor is of minimum capability and hence advantageously minimum cost. The host microprocessor is used to decompress the MPEG upper data layers. The more powerful the host microprocessor, the more upper data layers it decompresses. The remainder of the decompression (lower data layers) is performed by the MPEG dedicated processor and/or the graphics accelerator.

Abstract: The present invention relates to a bit-map compressing method and a bit-map compressing device. The bit-map data compressing method includes a main scanning step for scanning bit-map data in a main scanning direction; a first region separating step for separating a region including black pixels and a region including no black pixels in line unit; a secondary scanning step for scanning in a secondary direction perpendicular to the main scanning direction; a second region separating step for separating a region including black pixels and a region including no black pixels, in column unit; and an encoding step for encoding as an element each region obtained in the first region separating step and the second region separating step. Bit-map can be transferred by effectively performing data compression on simple algorithm, without using special hardware.

Abstract: An original image is encoded using difference signals that correspond to the difference between the original image and a blur image that approximates the original image. The blur image is generated using DC signals, wherein each DC signal corresponds to a different block of the original image.

Abstract: A zero-run-length encoder for a JPEG compression system comprises an addressable memory for storing 63 input values (quantized AC DCT coefficients), zero-detection logic, a shift register, a value generator, an accumulator, a Huffman encoder, done-detection logic, and last-value-detection logic. For each input value, the zero-detection logic stores zero/nonzero indications in a respective bit position of the shift register. The value generator includes a leading-zero counter that determines the number of leading zeroes in the leading fifteen bit positions of the shift register. This count is used to determine an offset value which is added to a previous address value (initially zero) to yield a present address value. The present address value is used to select a memory location from which an input value is read from memory into the Huffman encoder. The Huffman encoder generates an output code as a function of the addressed input value and the leading zero count.

Abstract: An image processing apparatus initially stores variable length codes corresponding to a significant frequency component, and variable length codes corresponding to a less significant frequency component If while storing the variable length codes into the storage means, it is detected that the storage means is full (with variable length codes), the control means makes room for the storage of further variable length codes corresponding to the more significant frequency component by canceling variable length codes stored in the storage means which correspond to the frequency component.

Abstract: In a communication method and apparatus, the load of a network is reduced by compressing data or changing the data compression method in accordance with a busy state of the network. A network's busy-state monitoring unit checks the busy state of the network, and data to be transmitted is compressed or the compression method is changed in accordance with the busy state, so that the amount of transmitted data is reduced, and the load of the network is reduced.

Abstract: A data compression system decorrelates input data into sets of frequency component data. Different sets of frequency component data are entropy encoded using different coding tables matched to the data values characteristic of the sets of frequency component data they are used to compress. Matching the coding tables to the sets of frequency component data improves compression. The order in which the data values from within each set of frequency component data is fed to the entropy encoder is varied to exploit any intra-set correlation.

Abstract: An image compression-coding device includes a level conversion circuit for adaptively reducing the amplitude of the quantification coefficient data based on statistical characteristics of the quantification coefficient data. The device further includes a selection circuit for selectively outputting either the quantification coefficient data after the level conversion or the quantification coefficient data before the level conversion, so that the image compression-coding device outputs a smaller amount of variable-length codes.

Abstract: A zig-zag and alternate scan conversion circuit for encoding/decoding videos which is structured only by logic circuits using a regularity of scan address patterns, thereby achieving an improvement in processing speed and a reduction in area.

Abstract: A compressing method consisting of generating a predicted value for the pixel of the digitized image to be compressed based on the values of at least two neighboring pixels is provided. After calculating the difference between the predicted value and the current pixel value, a prediction error is defined by a one-on-one mapping on the difference obtained. According to an advantageous feature of the mapping relationship, the required number of bits for representing the prediction error is less than that required for the difference per se. Afterwards, a parameter K is generated which is in proportion to the difference between the neighboring pixels used in prediction. According to the respective values of the parameter K, the next step is to encode each prediction error by assigning a variable-length Rice code to the prediction error of each pixel.

Abstract: A noise reduction apparatus in which decoded image data is input to a block division circuit which divides the input image into blocks each consisting of N.times.N pixels. A process block determination circuit determines the presence/absence of an edge from estimated values of four corner points of an objective block divided by the block division circuit. The process block determination circuit determines the size of a process block in accordance with the determination result. A linear interpolation circuit performs linear interpolation of the process block determined by the process block determination circuit, and outputs corrected image data.

Abstract: 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.

Abstract: An apparatus and computer-implemented method for decoding code words of an encoded bitstream associated with a variable-length code. According to a preferred embodiment, a processor forms a byte having BS bits in accordance with bits of the encoded bitstream and in accordance with any unused bits remaining after decoding a previous code word. The byte is applied to a table, and if the byte comprises at least one complete code word, then the table means produces at least one decoded symbol corresponding to the at least one complete code word, and a plurality of unused bits comprised of bits of the byte not within the at least one complete code word is determined.

Abstract: The invention implements a run-length file format with improved space-sav qualities. The file starts with a header in ASCII format and includes information such as the file format, maximum X and Y values, and a color palette. The binary raster data include at least one byte for each pixel run to indicate the color selected from the color palette and the run length. Concatenation flags demarcate groups of bytes. According to a first embodiment, each run is indicated by a variable-length sequence of bytes with the color in a fixed-length field and the repeat number in a variable-length field. According to a second embodiment, the color and run length are given in separate byte strings, each having a variable length. The file also includes line offset pointers to permit navigation of the file without decompressing it and thus to facilitate operations such as panning and zooming.

Abstract: A timing signal generator of an MPEG video decoder is responsive to a picture type signal for selectively generating one of a timing signal for decoding I and P pictures and a timing signal for decoding a B picture within a predetermined period of time, permitting an increased speed for the B picture decoding.

Abstract: Downsampling and inverse motion compensation are performed on compressed domain representations for video. By directly manipulating the compressed domain representation instead of the spatial domain representation, computational complexity is significantly reduced. For downsampling, the compressed stream is processed in the compressed (DCT) domain without explicit decompression and spatial domain downsampling so that the resulting compressed stream corresponds to a scaled down image, ensuring that the resulting compressed stream conforms to the standard syntax of 8.times.8 DCT matrices. For typical data sets, this approach of downsampling in the compressed domain results in computation savings around 80% compared with traditional spatial domain methods for downsampling from compressed data. For inverse motion compensation, motion compensated compressed video is converted into a sequence of DCT domain blocks corresponding to the spatial domain blocks in the current picture alone.

Abstract: A spatial compression and decompression system for color video data wherein a video stream is generated by a charge-coupled device with red, green and blue pixel elements. In a first compression stage, the 5-bit color data from each element is processed in turn. This step involves reading out from a lookup memory a 3-bit category (or compressed value) and 5-bit output value based on the 5-bit color data, a 5-bit previous value that represents same color data for a neighboring pixel and a 1-bit table select signal that determines in which of two similar tables the lookup is performed. The 3-bit category data for a pixel's three elements are combined and used as a 9-bit index into a Huffman table that performs the second stage of compression. Each Huffman table entry includes a variable-length Huffman code that represents more common categories with fewer bits, which provides additional compression over the first stage. The Huffman table reads out the code of the particular 9-bit category used for the lookup.

Abstract: An encoded video data re-compressing apparatus further compresses, for further transmission or storage, an encoded video data stream that includes quantization parameters and quantized coefficients without having to decompress the encoded video data streams and subsequently re-compress the decompressed video data. The encoded video data stream is parsed for extracting the quantization parameters and quantized coefficients from other side information. The quantized coefficients are either divided by a predetermined integer or selectively discarded to reduce the total number of bits. In the former case, the corresponding quantization parameters are multiplied by a predetermined integer. The manipulated coefficients and quantization parameters are multiplexed with the side information, such that they occupy the location of the corresponding original coefficients and quantization parameters in the video data stream.

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: A variable length coder is disclosed having a zig-zag FIFO that is supplied with coefficient blocks prior to encoding. The zig-zag FIFO has a comparator for comparing each coefficient of each coefficient block with zero. The zig-zag FIFO also has a counter responsive to the comparator. The counter increments a count therein by one for each received zero AC coefficient of each run, i.e., each continuous sequence, of zero AC coefficients contained in each block. The zig-zag FIFO also has a FIFO circuit which is responsive to both the comparator and counter. The FIFO stores each DC coefficient and each non-zero AC coefficient of each zig-zag scanned block in the order in which they are received. The FIFO also stores the count of the counter (i.e., the zero run length) for each run of zero AC coefficients in the order in which the run appears in the zig-zag scanned block of coefficients.

Abstract: A data encoding method apparatus in which the volume of arithmetic-logical operations for calculating the total number of bits required for encoding for adaptive bit allocation in the variable length encoding system for expediting the processing. In the data encoding apparatus for encoding and subsequently variable length encoding the input data, spectral data obtained on orthogonal transform coding are routed to a block floating circuit 403 for normalization and re-quantized in a quantization circuit 404 depending on the bit allocation number information from a bit allocation calculating circuit 406 so as to be then variable length encoded by an encoding circuit 407 and outputted at an output terminal 408.

Abstract: A method is provided for performing statistical decoding if a symbol in a data stream having byte boundaries wherein the symbol may have varying alignments with respect to the byte boundaries. The next byte of data is fetched from the data stream wherein the fetched byte contains at least a portion of the symbol. Based on this byte and on the current bit position, which is maintained by a state machine, either (a) a decoded value is obtained from a lookup table, or (b) further bytes are fetched and used to determine the decoded value. Each symbol has a prefix and free bits wherein the entire symbol may be included in the next byte, a boundary of the next byte may fall within a prefix, or a boundary of the next byte may fall within the free bits depending on the alignment of the symbol. Differing action routines, corresponding to differing symbols, may be selected for execution according to the decoded values determined in the symbols.

Abstract: A method and apparatus for encoding and decoding image data in which continuous still images are compressed and decompressed. The apparatus divides a plurality of multivalue image data into blocks each comprising a plurality of pixels, the pixels in the block are orthogonal converted and compressed, and the original image data is decompressed from the encoded data. The apparatus detects the block having an image change as an effective block. For a macro block including a plurality of effective blocks, a compressing order of the macro blocks is decided by the order according to appearance frequencies of the effective blocks or a predetermined order and the image data is compressed every macro block. As encoded data, the order information and code information of the macro block are sequentially transmitted. In this instance, the code amount is monitored. When the code amount exceeds a predetermined threshold value, the compression is stopped and the compression of the next image is performed.

Abstract: An encoded video data re-compressing apparatus further compresses, for further transmission or storage, an encoded video data stream that includes quantization parameters and quantized coefficients without having to decompress the encoded video data streams and subsequently re-compress the decompressed video data. The encoded video data stream is parsed for extracting the quantization parameters and quantized coefficients from other side information. The quantized coefficients are either divided by a predetermined integer or selectively discarded to reduce the total number of bits. In the former case, the corresponding quantization parameters are multiplied by a predetermined integer. The manipulated coefficients and quantization parameters are multiplexed with the side information, such that they occupy the location of the corresponding original coefficients and quantization parameters in the video data stream.

Abstract: An image signal coding device capable of attaining a high-speed coding operation without increasing a circuit scale. The image signal coding device includes a DCT section for performing two-dimensional orthogonal transform to each of plural pixel blocks obtained by dividing an image signal to generate a transform coefficient, a linear quantization section for linearly quantizing the transform coefficient by using given quantization characteristics to generate a quantized coefficient, and a variable length coding section for performing variable length coding to the quantized coefficient to generate code data. The image signal coding device further includes an effective region holding section for holding region information including a range of the transform coefficient to be linearly quantized by the linear quantization section and a range of the quantized coefficient to be coded by the variable length coding section.

Abstract: A fax selective call receiver system (10) featuring compression of a fax message with an optimal one of a plurality of compression code-books (50). At least a portion (44) of a source document (26) is compressed with each of a plurality of code-books (50) and the smallest resulting data file is selected as the optimal compressed file. The compressed data file is transmitted to a selective call receiver (40) together with an index identifying the optimal code-book. The selective call receiver (40) stores each of the plurality of code-books and accesses the particular code-book for decompressing the data file on the basis of the received index. In an alternative embodiment, the fax message is divided into composing segments (SI1, SI2 and SI3) and each segment is compressed with each code-book to determine the optimal code-book for each segment.