Abstract: This invention relates to a coding method, code converting method and apparatus, and image forming apparatus and, more particularly, to a coding method, code converting method and apparatus, and image forming apparatus capable of high-speed conversion data coded by different coding method. When data is converted between different coding methods, e.g., when data encoded by a run-length coding method is re-encoded by a coding method using typical prediction, the data is conventionally temporarily decoded into original data before encoding and then re-encoded. In this invention, data subjected to coding such as MH, MR, or MMR as run-length coding is decoded into run-length information as intermediate data, and typical prediction is performed in this state. This increases the speed of conversion from run-length coded data to coded data using typical prediction.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

Abstract: A three-dimensional color ultrasonic encoding and/or decoding system is provided in which a three-dimensional color ultrasonic image is classified into zero pixel data, gray pixel data and indexed color pixel data, to thereby perform encoding and decoding based on the classification data. The encoding and/or decoding system includes an encoding system including a classifier, a first encoder for encoding gray pixel data and a second encoder for encoding indexed color pixel data, a run-level encoder, a pixel separator and a multiplexer, and a decoding system including a demultiplexer, a run-level decoder, a first decoder for decoding gray pixel data, a second decoder for decoding indexed color pixel data and an image mixer.

Abstract: An image decoding method is provided for decoding each block of a digital image divided into a plurality of blocks, from a coded image signal including codewords of the each block and codewords of coding mode information of the each block, the method comprising separating the codewords of a target block and the codeword of coding mode information of the target block from the coded image signal, decoding the coding mode information of a target block from the separated codeword of the coding mode information using a codeword table.

Abstract: A block based hybrid compression method with compression ratio control. The input page is classified as SOLID, TEXT, SATURATED TEXT or IMAGE type, and the compression method most appropriate for each class is chosen on a block by block basis. The compression methods shown include Block Truncation Coding, Lossy or Lossless Differential Pulse Code Modulation, Run Length Coding and Discrete Cosine Transforms, but other algorithms may also be used. The compression ratio is dynamically controlled by selection of the compression algorithm, and by the adjustment of control parameters on a block by block or a row of blocks basis. The methods shown will execute very efficiently on a Texas Instruments TMS302C82 multiprocessing Digital Signal Processor.

Abstract: The present invention provides a data compression method in which a plurality of consecutive characters of a data string to be compressed are set as a character string to be searched for. Bits of a bit string representing the set character string are allocated to at least two codewords. Thus, first and second searching codewords are generated. These first and second codewords are used as array addresses. Fist and second array tables are prepared, in which information on the past occurrence positions of the set character string is previously entered as the contents thereof. When the first and second codewords are generated from the character string to be compressed, the first and second array tables are looked up by using these codewords as the addresses of the arrays. When results of looking up these tables match with each other, it is found that the set character string occurred in the past.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

Abstract: A picture data encoding apparatus includes a target bit amount determining part for calculating a target bit amount for each block according to a bit rate and a number of blocks to be converted; and a bit amount adjusting part for reducing a bit amount for each block to the target bit amount by means of reducing the bit amount for each code by converting run level information for each code into lower run level information.

Abstract: Compression of digital ink is achieved by calculating second order differences between consecutive elements in the digital ink and applying the differences to a Huffman encoder to produce a compressed bitstream. For digital ink that is not highly correlated, compression may be achieved by representing segments of the digital ink by mathematical shapes such as a Bezier curve or orthogonal elements and transmitting the shape instead of the digital ink.

Abstract: An image compression apparatus compresses image data by carrying out a parallel processing for every image pattern made up of a plurality of bits. The apparatus includes a first unit for obtaining a run length of the image data and a repetition number of the run length, a second unit for coding the run length and the repetition number obtained by the first unit, and a third unit for predicting whether or not a code length of a code generated by a word which is to be coded by the second unit exceeds a predetermined threshold value, based on the run length and the repetition number obtained by the first unit. The second unit carries out a pass coding to output the image pattern as it is when the third unit predicts that the code length exceeds the predetermined threshold value.

Abstract: A method for compression of an input image that includes a plurality of pixels having respective input pixel values. The method includes quantizing the input pixel values so as to generate respective quantized pixel values, and generating a quantized image by substituting the quantized pixel values for the respective input pixel values in the input image. The input pixel values in the input image are reordered so as to generate a reordered image in which the input pixel values are grouped by their respective quantized values. The quantized image and the reordered image are compressed so as to generate a compressed output image file.

Abstract: An image processing apparatus for inputting image data from an external image input device and outputting the inputted image data to an external image output device after processing the data, the image processing apparatus including a data compression device for compressing the inputted image data by a variable-length data compression method. An image data storing device stores the inputted image data therein. A control device controls the apparatus, such that, when a size of an output image of the inputted image data is larger than a predetermined size, the data compression device compresses the inputted image data by the variable-length data compression method and the image data storing device stores the compressed image data therein, and, when the output image of the inputted image data is equal to or smaller than the predetermined size, the image data storing device stores the inputted image data therein without data compression.

Abstract: An apparatus and a method of changing a bit rate of a compressed image bit stream by changing a codeword so as to easily change the bit rate and reduce a changing loss. The apparatus for changing a bit rate, in which an input bit stream generated by an image compression encoding method is changed into an output bit stream having a desired bit rate, includes a changing codeword determiner which selects codewords to replace the codewords of the input bit stream, and a codeword changer which changes the codewords of the input bit stream into the codewords selected by the changing codeword determiner. The method and the apparatus can be applied to image services provided through the Internet and receiving apparatuses supporting the Personal Video Recorder (PVR) function. Particularly, the method of changing the bit rate of a compressed image bit stream changes the codewords of input transform coefficients so as to easily change the bit rate and reduce the changing loss.

Abstract: A run-length based decoder for decoding compressed image data while allowing error to be contained with the length of a code word. The decoder includes: (a) a shifter for outputing Q+1 number of N-bit data streams; (b) Q+1 code comparators to respectively receive the data streams from the shifter; (c) a code type arbitrator which includes a multiplexer to receive output signals from the Q+1 number of code comparators, and output the data stream received from the code word comparator which also outputs the verification signal; (d) a shift number generator connected to the code arbitrator to receive the N-bit data stream from the code arbitrator and generate a new_shift_number to the shifter according to the number of bits associated with the code word pattern of the N-bit data stream; and (e) a code interpreter which is also connected to the code arbitrator to receive to decode the N-bit data stream into pixels.

Abstract: A scheme for detecting telop character displaying frames in video image which is capable of suppressing erroneous detection of frames without telop characters due to instability of image features is disclosed. In this scheme, each input frame constituting the video data is entered, and whether each input frame is a telop character displaying frame in which telop characters are displayed or not is judged, according to edge pairs detected from each input frame by detecting each two adjacent edge pixels for which intensity gradient directions are opposite on some scanning line used in judging an intensity gradient direction at each edge pixel and for which an intensity difference between said two adjacent edge pixels is within a prescribed range as one edge pair, edge pixels being pixels at which an intensity value locally changes by at least a prescribed amount with respect to a neighboring pixel among a plurality of pixels constituting each input frame.

Abstract: The present invention relates to an image coding apparatus/method, an image decoding apparatus/method, and a transmission medium, which conduct high-efficiency coding or decoding of an image, and applicable in a system performing efficient transmission or accumulation of images. In coding an image after splitting the image into a plurality of bands, the invention is characterized in a process comprising the steps of splitting the image into a plurality of bands, applying quadrature transformation to the images of the resultant band components, quantizing the resultant quadrature transformation coefficients, and generating a coded bit stream by variable-length-coding the quantization coefficient. This permits coding less susceptible to block strain at a high compression ratio.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

Abstract: An image storage and processing method constructs, clips, fills, and combines arbitrary 2-dimensional shapes in an advanced graphics system. The method supports processing of anti-aliased images by compressing the image into a novel AlphaRegion data structure. AlphaRegion encodes into the data structure both the partially transparent as well as the fully opaque alpha values of an image according to rectangular bands. A band is a contiguous series of scan lines that have the same pattern of alpha values in a single direction. AlphaRegion encoding results in a more compact representation than possible in a conventional bitmap, but without losing the anti-aliasing features. AlphaRegion can be constructed either by supersampling sub-scan lines of an image, from the scan lines of a gray-scale image, from an existing conventional 1-bit Region or alpha mask buffer, or directly from a scan-line conversion of a geometric shape. AlphaRegion stores image data into three arrays, yInfo, xInfo and alphaData.

Abstract: An encoder reorders quantized wavelet coefficients to cluster large and small wavelet coefficients into separate groups without requiring the use of data-dependent data structures. The coefficients are then adaptively encoded based on a run-length code which continuously modifies a parameter that controls the codewords uses to represent strings of quantized coefficients, seeking to minimize the number of bits spent in the codewords. A matrix of indices contains the coarsest coefficients in the upper left corner, and filling in low high and high low sub bands in larger and larger blocks in an alternating manner, such that low high sub bands comprise the top of the matrix and the high low sub bands comprise the left side of the matrix. The shortest codewords are assigned to represent a run of the most likely character having length of 2k, where k is a parameter. k is adjusted based on successive characters being encountered.

Abstract: An image compression/decompression method is provided to improve the speed of data processing after the AD converter outputting the data scanned. The present invention defines a byte as having an attribute code and a counter. Each image data is processed according to the bit planes from high bit to low bit. Every data access to the output data of the A/D converter can read 63(26−1) bytes. The attribute code of each byte represents the type of the encoded codes, such as high/low bit or un-encoded data. The counter, on the other hand, would count the number of consecutive bits having the same value. The encoded image data will be output to a RAM for the host computer to access. For decompression, the host computer will access the RAM. The host computer only need to request the attribute of the data byte to know if the encoded data is high/low bit or un-encoded data.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

Abstract: The speed of decoding processing for variable-length coded image data is improved.

Abstract: An apparatus for encoding image data of the present invention is provided with a one-dimensional encoder which encodes image data one-dimensionally, a two-dimensional encoder which encodes image data two-dimensionally, a thin line determination section which determines the frequency of occurrence of short run-length from a run-length count value during encoding of lines applied with the one-dimensional encoding, and an encoding control section which, when it is determined from the determination result in the thin line determination section that the frequency of occurrence of the short run-length is high, restricts the number of lines which are applied with the second-dimensional encoding within a predetermined range.

Abstract: A set of processes are disclosed for compressing and decompressing bitmapped picture files that are to be stored for later display within a control for an HVAC system. The compression process includes an examination of the first bitmapped pixel in a given bitmapped file followed by a counting of the number of consecutive pixels having the same state as the first pixel. The process continues with analyses of successive numbers of pixels of first one state and then another state and generating a numerical representations as to each number of so counted pixels until the last pixel of the bitmapped picture file data is analyzed. The resulting compressed file is stored in a memory within a control for an HVAC system so that the file can thereafter be read when the file is to be displayed.

Abstract: An image encoding apparatus (FIG. 4) is configured to receive data defining respective colour values for pixels arranged in rows and columns (FIGS. 1 and 2) to make up an image. The apparatus being applies coding for the pixel color values, suitably through run-length encoding, to provide image compression. The apparatus is configured to encode images as either sequential rows or sequential columns of pixel data, in dependence on which direction requires less storage. A reconfiguration of the apparatus (FIG. 4), as a decoder for such compressed images, is also provided.

Abstract: A fast, raster-based, enhanced, data compression technique for the printing of compound documents, including pre-processing images in an original page description form of the data before the page data is rasterized, greatly improving compressibility. Unscaled image data is filtered before it is rasterized to the final printing resolution. The filtering specifically enables a separate, near loss-less, compression algorithm to operate on a rasterized page description with high compression ratios. A data compression technique enables a system to compress compound document using a relatively fast and simple algorithm with near loss-less print quality.

Abstract: A simple, cost-effective compression circuit which compress raw color data without interpolation. Control points common to all the colors in a line are generated each time one of the colors exceeds the color change threshold. The change in the other color is recorded at the same time even though it doesn't exceed the minimum change threshold.

Abstract: The digital still camera of the present invention includes: a microcomputer for controlling the camera and for performing the compression coding and the expansion decoding on images; an image photographing unit for converting images into electric signals using a CCD; a memory for temporarily storing information of photographed images to perform the compression coding and the expansion decoding on the images, the memory including a RAM used for the operation of the microcomputer and a ROM for storing a control program for controlling the microcomputer; a memory card for storing data of compressed images obtained after the photographed images are subjected to the compression coding; and a liquid crystal display unit for displaying the photographed images.

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: 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 runlength encoding, but the number of drawing primitive calls required to render the compressed images directly is substantially less. If the size of the largest area exceeds predetermined limits it is subdivided into smaller areas automatically without having to specify the size and position.

Abstract: A system for the efficient decoding of data encoded with variable length codes uses an N-bit buffer as an index to a data look-up table or other suitable data structure. The encoded data is stored in an encoded data storage area and extracted N bits at a time. The N bits are used as an index or indicator to a location within the data look-up table. The contents of the data look-up table in the indicated location correspond to one or more decoded tokens and also provide an indication of the number of data bits from the N-bit buffer that were used to represent the decoded tokens. A pointer is incremented by the number and indicates a location within the encoded data storage area where the next N bits will be extracted and stored in the buffer. If the N-bit buffer is greater than or equal to the maximal length for the variable codes, at least one valid token is guaranteed as a result of a single data look-up operation. However, a data look-up operation typically results in a plurality of decoded tokens.

Abstract: A method for lossy compression of digitized images involves wavelet transformation, extension of image dimension factors with allocation to memory, and discrete wavelet transformation.

Abstract: A decoding apparatus comprises: decoding means which receives a first code sequence of a hierarchical structure as an input, decodes a code sequence of a selected first layer and higher layers in the first code sequence, outputs a detection signal when an error is detected while the code sequence is being decoded, and detects a second code sequence indicating the start of the first layer and higher layers in a set code sequence parsing position of the first sequence; and means for setting a code sequence parsing position which receives the detection signal and sets the parsing position of the code sequence in such a way that code sequence parsing performed by the decoding means is returned from a point at which code sequence parsing is being performed to a point at which code sequence parsing has been performed in the first code sequence.

Abstract: A memory device memorizes the multiplex data of compressed picture data and compressed subordinate picture data. A data-separating section separates the subordinate picture data and a subordinate-picture-decoding section decodes the separated subordinate picture data into the run-length-decoded data. A subordinate-picture-data-converting section changes the format of the decoded subordinate picture data to reduce the number of table-looking-up operations required for a synthesizing process and removes the redundant pixel data which is included in the decoded subordinate picture data and whose contrast values are zero and hence which can not be seen even if synthesized. A picture-synthetic section synthesizes the subordinate picture data converted by the subordinate-picture-data-converting section on the main picture at the designated synthesizing positions.

Abstract: An image decoding method is provided for decoding each block of a digital image divided into a plurality of blocks, from a coded image signal including codewords of the block and codewords of coding mode information of the block. The method comprises separating the codewords of a target block and the codeword of coding mode information of the target block from the coded image signal, and decoding the coding mode information of the target block from the separated codeword of the coding mode information using a codeword table. The codeword table is selected from a plurality of codeword tables by referring to a combination of coding mode information of previously decoded blocks at the periphery of the target block, the codeword tables each having codewords, each codeword being determined based on a combination of coding mode information of previously decoded blocks at the periphery of the target block.

Abstract: An image decoding method is provided for decoding each block of a digital image divided into a plurality of blocks, from a coded image signal including codewords of the each block and codewords of coding mode information of the each block, the method comprising separating the codewords of a target block and the codeword of coding mode information of the target block from the coded image signal, decoding the coding mode information of a target block from the separated codeword of the coding mode information using a codeword table.

Abstract: An image coding method for coding each block of a frame of a digital image divided into a plurality of blocks is provided, where each block has a plurality of pixels, the method comprising determining a coding mode for a target block to output mode information of the target block, coding the mode information of the target block using the mode information of at least one previously coded block of the frame at the periphery of the target block, and coding the digital image in the target block according to the mode information of the target block.

Abstract: The image data is divided into groups of a predetermined fixed length, and the divided groups are simultaneously compared to predetermined patters for the entropy encoding to render a display image in the video memory unit. Because of the above processing, the encoding process is rapidly performed, and the processing speed is lower that that of prior art image processing techniques that do not involve data compression. Thus, the above described process is comparable in image rendering to prior art techniques that do not involve encoding and decoding. Because of the encoding compression, the video memory is efficiently utilized, and the video memory capacity is reduced.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and a reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

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: The present invention provides a variable-length encoding and decoding apparatus which, when an overlap of a variable-length code and a synchronizing word is generated on a bit stream due to a transmission error or the like in the variable-length encoding and decoding apparatus of an image compression bit stream, can exactly detect the synchronizing word and a state where the overlap is generated.

Abstract: In an image coding method of the present invention, after a process such as DCT is performed to digital image data, quantization process is performed, and then, to resultant quantized transform coefficients, variable length coding process is performed with reference to a variable length code table showing how variable length codes are allocated, and in a comparison process between an event derived from the quantized transform coefficients and reference event included in the variable length code table, transformation process is performed to increase a possibility of performing variable length coding with satisfactory coding efficiency.

Abstract: A method for compressing 4D image data to accelerate the visualization of the data comprising the sequential steps of compressing a first 3D image using run length encoding (RLE), detecting changes between the first 3D image and subsequent time varied 3D images by dividing each subsequent time varying 3D image into a plurality of sub-volume voxels and performing a chi-squared test on corresponding voxels contained in each subsequent time varying 3D image and the sub-volume voxels in which was last detected a change, and compressing the data of each, subsequent successive time varying 3D image using run-length encoding.

Abstract: With facsimile apparatuses wherein color image data is coded, a facsimile on a calling side codes image data by replacing the image data with a codeword indicative of a white run-length or a black run-length, represents color information by combining specific codewords among the codewords and represents image data including color image only by codewords by combining the coded image data and the color information. A facsimile on a called side receives transmitted image data, determines color information represented by a combination of specific codewords among the codewords in the received image data, and outputs image data as specific color image when the color image is determined.

Abstract: Digitalized video images are compressed in several steps in order to provide a system for transmitting moving video pictures via narrow band channels, such as the telephone network. The system is based on any extension of the bit-plane coding technique to video sequences and lossy conditions. The compression technique can also be advantageously used in a lossless compression system. The system involves the steps of bit plane representation and skipping the least significant bit plane(s), shifting the pixels, coding with a Gray code, the use of segmentation, and motion-estimation/motion compensation and application of a transmit/not transmit/motion compensate (TX/NT/MC) procedure, exploiting of the temporal redundancy of two corresponding bit planes via an XOR operation on two successive images, and a plane-by-plane application of an extended RLEID technique.

Abstract: A run length codeword system which has a set of codewords, each codeword being one byte. The first codeword of a run is divided into a 4-bit code part and 4 bits of printing hints. The code part specifies the source of the data, and the format of the remaining bytes in the run. The remaining one or two codewords specify the number of remaining data bytes in the run, or color values.

Abstract: An image is coded by counting runs of non-background picture elements, and counting consecutive scanning lines having only background picture elements. Consecutive scanning lines of this type are coded as a single command and value, giving the number of scanning lines. Consecutive scanning lines having identical numbers of runs of non-background picture elements are coded as another single command and value, giving the run count, followed by run information describing each run. Sparse images, consisting mostly of background area, can be coded efficiently in this way.

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: Conversion of JETSEND-compressed image data into PCL raster image data compatible with a PCL printer. The JETSEND-compressed image data is not decompressed prior to conversion of PCL raster image data, but rather is converted to a PCL raster image in situ by monitoring control byte information in the compressed image data so as to determine where one scan line ends and another begins.

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.