Abstract: This invention is a method and apparatus for processing compressed digital images. More particularly, this invention relates to methods and apparatus which accomplish rotation in conjunction with a variable-length decompression operation. A small amount of auxiliary information consisting of pointers to the starts of the scanlines is stored along with the DC coefficients in the decompressor, instead of the compressed image, to reduce the memory requirements for orthogonally rotating an image.

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: A method and apparatus incorporating a binary function correlation of run edges for compressing periodic halftoned digital images while increasing compression ratios over currently known one- and two-dimensional and adaptive arithmetic methods and decreasing the time required to perform the operation. In one embodiment, the invention horizontally encodes an image's run edges located at or near least &tgr; pixels ahead of a reference run edge in raster sequential image data. After the image is divided into lines of digital bits containing digital information indicative of binary values, the lines are encoded. A value for &tgr;—where &tgr; is independent of the width of the image and represents the periodicity for an edge of a run—is selected. Thereafter, run edges located &tgr;±n pixels ahead of a designated run edge of a reference run are encoded.

Abstract: A method and system of encoding and decoding image data in images having less than 128 distinct colors. Eight bit data bytes representing the color of each pixel data are re-indexed for each pixel to seven or less bits, and a sub-palette stores the relationship between the re-indexed colors and the original eight-bit color values. The remaining bits in the byte store run lengths of pixels that have contiguous colors. Further data compression is achieved by grouping pixels into rows, eliminating any duplicate rows and identifying the pixel data by a series of row pointers. Still further compression is accomplished by dropping representations of transparent pixels from the end of rows and representing a number of transparent pixels at the beginning of rows with a single byte. The compressed data is efficiently decoded using the row pointers to expedite vertical clipping of the image and adjusting horizontal clipping for leading and trailing transparent pixels.

Abstract: A method of compressing a bitmap of a symbol includes dividing up the symbol into one or more strokes which include a number of parallel, laterally adjacent, continuous line segments, run-length encoding each stroke to form a stream of line codes for that stroke, where the stream of line codes provides absolute values for position and length of one line segment and relative values of position and length for the other line segments; and then presenting the streams of the line codes in sequence, as a set representing the symbol.

Abstract: For compressing M-bit data words where M is a plural positive integer, groups of N data words are defined, where N is a plural positive integer, and then the bits of the group of N data words are output as a bit stream including a sequence of sub-streams, each sub-stream relating to a respective bit position in the N data words and being formed from a sequence of N data bits from that bit position of respective data words. The bit sequences are run length encoded and the run length codes thus generated are further encoded using a commaless code such as a Huffman code.

Abstract: In a data compression system for compressing an input stream of characters into a compressed stream of codewords by employing a dictionary, wherein the dictionary stores a plurality of entries of characters, each entry being identified by a unique codeword, the input stream of characters is parsed into parsed strings and the unique codeword identifying each parsed string is transmitted. In the meantime, the dictionary is updated with N new entries of characters, wherein all of the N new entries include an unmatched character which is appended to the parsed string so that a new codeword is assigned to each of the N new entries, N being an integer equal to or larger than 0.

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

Abstract: A system and method for processing image data from a document and for producing a compressed binarized version of the image data for transmission to or use by subsequent users. Processing of the image data is done in parallel after the scanning of the document is started but before the entire document is scanned. A splitter is used to divide a scan line of image data produced by an imager at the scan line into a plurality of channels, with each channel having at least one overlap area of pixels and with the overlap areas of pixels being used to avoid errors between channels. Thresholding and compression are performed by each one of the channels in parallel. The compression is performed in a direction which is perpendicular to the direction of scanning and conforms to a standard compression algorithm like CCITT Group 4.

Abstract: What is disclosed is a method for run-length encoding of a multi-colored image having the steps of first receiving a first color value, a second color value, and a third color value. Then, comparing a current color value with the third color value; and comparing the third color value with the first color value. If the current color value is not equal to the third color value, then capturing a run length and a run color value; and, if the third pixel value is equal to the first pixel value, then generating a codeword with the run length and the run color value. An apparatus for performing the above steps are also disclosed.

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

Abstract: A 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: Compression and decompression methods for transmitting facsimile images in which the facsimile image is compressed in both vertical and horizontal directions are implemented using two dimensional maximum differences algorithms. Asymmetrical and fractional image compression are provided by controlling the number of lines, i.e., rows or columns, being compressed and by controlling the bit segment length used during each differences determination. The compressed facsimile image is decompressed by selecting a reference bit in the decompressed facsimile image and expanding the bit in both vertical and horizontal directions in accordance with a binary value of bits near the selected reference bit. A transmission channel adapted to serially perform the encoding and decoding functions is also described.

Abstract: An electrophotographic image forming apparatus transfers image information relating to an image to be formed on a medium, while maintaining desired low levels of electromagnetic emissions. The apparatus includes an image processor that generates low-frequency image information signals containing the image information. A low-frequency interface is connected to the image processor for transferring the low-frequency image information signals. A control circuit, connected to the low-frequency interface, receives the low-frequency image information signals generated by the image processor. The control circuit operates on the low-frequency image information signals to form a high-frequency image information signal therefrom, where the high-frequency image information signal contains the image information. The apparatus also includes a high-frequency interface connected to the printhead control circuit for transferring the high-frequency image information signal.

Abstract: First data representing a picture is quantized into quantization-resultant data. Information corresponding to a predetermined special effect on a picture represented by the quantization-resultant data is generated in response to the quantization-resultant data. The quantization-resultant data is converted into conversion-resultant data. The conversion-resultant data and the information are multiplexed into multiplexing-resultant data. The multiplexing-resultant data is compressed into compression-resultant data of a predetermined code.

Abstract: This invention provides a mode determination system for maximizing the coding efficiency by minimizing the amount of generated encoded information. An intra-frame picture signal X of 16 pels 16 lines is divided into four sub-blocks of 8 pels.times.8 lines by a DCT block dividing unit. A DCT block dispersion calculation unit calculates the dispersions of the four sub-blocks, and a nonlinear function transform unit transforms the dispersions to values for estimating amounts of generated encoded information. An adder unit adds together the four values for estimating amounts of generated encoded information and outputs the sum. On the other hand, a motion compensated predictive difference Y of 16 pels.times.

Abstract: Already stored uncompressed raster data are selectively compressed before any new raster data can be processed and stored. Both compressed and uncompressed raster data is preferably stored in the same size blocks, and the Raster Objects are preferably divided at Render Swath boundaries. Assuming that the Raster Object data has been or will be compressed by means of a known dither matrix, that dither matrix is used in the compression process to eliminate all but the data essential to reconstruct the dithered image, and the pixels of the original image are preferably successively processed along a predetermined scan path and the resultant linear pixel array is divided into successive runs which may each be encoded such that when those encoded runs are assembled into a replica of the original image and both the original image and the replica image are dithered with the same predetermined dither matrix, the dithered replica image is identical to the dithered original image.

Abstract: Image to be transmitted is divided into blocks. The block size varies in each stage of transmission. The blocks are down-sampled to a fixed size for polynomial approximation coding (PAC). The PAC's are derived from a regressive model which is a statistical tool for data analysis. A two-dimensional polynomial equation is used to approximate the relation of the image data and their positions. The coefficients of the 2-D polynomial equation is coded and transmitted to represent the initial image. In the next stage, same or similar coding is conducted to the residual image. After a decided number of stages of transmission an approximated image is reconstructed. A novel iterative coding system for progressive image transmission is disclosed.

Abstract: A method of run-length encoding an image containing runs of white pixels and black pixels, by acquiring the image to encode; determining the length of all unique pixel run-lengths contained within the image on a line-by-line basis, irrespective of pixel color; selecting a base of a numeral system, where the base is made up of digits; generating a number of unequal-length codewords equal to the base; determining, in order, pixel run-lengths, on a line-by-line basis, for each pixel run-length contained in the image, where counting on each line starts with a particular pixel color; representing each pixel run-length determined in the last step in the numeral system of the base; determining the frequency of occurrence of each digit resulting from the last step; assigning the unequal-length codewords, according to ascending length of the unequal-length codewords, to the digits according to descending order of frequency of occurrence of the digits; and encoding the image by replacing each pixel run-length in the im

Abstract: A DCT based lossy compression method for compressing a digitized image composed of a matrix of image samples to provide a compressed image which satisfies a predefined bit budget. The digitized image is first sub-divided into blocks (e.g. of size 8.times.8 pixels). A discrete cosine transform (DCT) comprising a set of DCT coefficients is then derived for each block. A quantization table is selected from a set of quantization tables and, using the selected table, the coefficients of each DCT are quantized. A zero-value index, corresponding to the average number of zero value quantized DCT coefficients per DCT, is determined. A predicted zero-value index is calculated using said predefined bit budget and a quantization table selected from said set of tables using the determined index and the predicted index. Using that selected table, the unquantized coefficients of the DCTs are re-quantized and the requantized coefficients compressed using run-length encoding and Huffman encoding.

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: 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: A method, apparatus and article of manufacture performs an image processing operation directly on the runs of a runlength encoded bitmap of pixels. In the method, a first selection step selects, in the first instance, at least two runs from one or more series of runs of one or more images on the basis of pixel position information. A runlength processing operation is then performed on the selected runs in accordance with the image processing operation in order to obtain a resultant run having a resultant runlength and a resultant pixel value. In a shortening step the runlengths of the processed runs are shortened by a value derived from the determined resultant runlength. In a step size determining step a step size is derived from the resultant runlength.

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: A target code length is designated at a code length designation unit, and the entire input image data is encoded by a continuous gradation region encoding unit to obtain the target code length. On the other hand, a region segmentation unit segments the input image data into regions, a limited color region encoding unit encodes limited color regions of the segmented regions, and the continuous gradation region encoding unit encodes continuous gradation regions, so as to obtain the target code length. Either the codes obtained when the entire input image data is encoded or the codes obtained when the image data is encoded by the limited color region encoding unit and continuous gradation region encoding unit in units of regions are output on the basis of the coding unit of the codes of the entire input image data, and the coding unit of the codes of the continuous gradation region.

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: The present invention relates to a process for producing a skeleton from a binary image by using the compressed run data of the image instead of using natural expanded binary format of the image. A run length compressed image is a binary image (black/white) that is compressed by taking stripes of pixels of the same value and grouping them together into a single "run" of pixels. This compression technique saves significant amounts of memory on most binary images. It is an object of this present invention to enable the image to be skeletonized in its run length compressed format. This reduces the amount of data that needs to be stored in memory. Further, since the image is in "runs" and not pixels, the pixels that are not affected are not evaluated. By increasing available memory while reducing the amount of pixels to be evaluated, the speed for the process is increased on the order of several magnitudes.

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: First data representing a picture is quantized into quantization-resultant data. Information corresponding to a predetermined special effect on a picture represented by the quantization-resultant data is generated in response to the quantization-resultant data. The quantization-resultant data is converted into conversion-resultant data. The conversion-resultant data and the information are multiplexed into multiplexing-resultant data. The multiplexing-resultant data is compressed into compression-resultant data of a predetermined code.

Abstract: A simple method of anti-aliasing for edges near the fast scan direction is to replace the pixels on both sides of the transition in a scan with pixels of varying intermediate color. Thus, if there is an edge between red and blue areas, instead of there being an abrupt change from red to blue at the edge, there will be a number of pixels that slowly vary from mostly red to mostly blue, which will tend to make the jagged edge less obvious.

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: Compressing graphic data for a first computer system, e.g. an emulated system, on a second computer system. For each scanline of the graphic data for the first computer system, a number of colors present on the scanline are counted. A new color palette for the scanline is formed at a reduced representation. Then, a representation of each color of each pixel on the scanline is converted to the new palette. The scanline is then run-length encoded. The graphic data is compressed so that it can be, for example, transmitted between a client (e.g. an X client) and a server (e.g. an X server) and conserve network bandwidth.

Abstract: A contour decoding apparatus decodes a bitstream of contour information which was encoded using a chain code. A demultiplexing unit separates the bitstream of the contour information into start contour pixel information and chain code information. A start contour pixel decoder decodes start contour pixel information separated by the demultiplexing unit and outputs horizontal and vertical coordinate values of the start pixel.

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: Pixel-based image data are subsampled for transmission to a printer and later bilinear interpolation in the printer. The transmission system evaluates the error that will remain after interpolation. In response to this evaluation, the transmission system also forms trim data for later application to the interpolated subsample to remove a significant part of the error. Preferably trim data points are selected based on relative importance of the associated correction--specifically, size of the error that will remain after interpolation--but also the amount of trim data is controlled to maintain a significant advantage in overall transmission time, relative to transmitting the entire image-data set. The amount of trim data is held roughly to a certain fraction, about five percent, of the number of points in each data block (e. g., swath), essentially independent of the error evaluation.

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: A recording and reproducing apparatus is disclosed. Each of main pixel blocks of (m pixels in a horizontal direction.times.m pixels in a vertical direction.times.n pixels in a time direction), m and n being an integer, included in a video signal is divided into a first and a second block. The horizontal pixel number of the first block is made half and the vertical pixel number of the second block is made half. Correlation between continuous two main pixel blocks is detected in the horizontal and vertical directions. Three-dimensional orthogonal transform is applied to either of the first or the second block according to the detected correlation. And, the video signal, the first or the second block thereof being applied with the three-dimensional orthogonal transform, is encoded to form a signal to be recorded. In reproduction, the formed signal is decoded.

Abstract: A high definition graphic display apparatus comprises a polygon data inputting means for producing polygon data including coordinates to be displayed; an N times coordinate conversion means for expanding each coordinate value N times; an active list producing means for producing an active list which includes active cells each including information of an X coordinate which has N-times expanded coordinates which represent inclination of a side, and a number of Y coordinate lines which intersect the side, a scan list producing unit for producing a scan list by finding a line scan list of every scan line with a point on a side corresponding to the active cell which is present on the scan line; a scan line information extracting means for deciding whether an unit N lines is directly convertible into compressed display data, the unit N lines which includes a Y coordinate line; a compressed data producing means for producing compressed display data in accordance with an output of the scan line information extracting

Abstract: At the encoding side, a sum of code lengths of a block is calculated and stored in a memory for each of block lines (stripes); and at the decoding side, when decoding of one block is completed, a head address of a code in the next block is calculated utilizing a sum of an amount of codes utilized for the decoding operation and code lengths for each of the stripes. The rotation process of an image utilizing encoded data is performed in accordance with the head address. Further, at the encoding side, colors of pixels in a predetermined block is determined, and encoding operation is performed block by block for only those blocks including pixels of different colors. At the decoding side, an address of block data for sequentially constructing a rotated image is controlled to decode the pixels in the block, and finally the rotation process is performed on the pixels in the block in accordance with the color of the pixels.

Abstract: A data encoding system for encoding input color pixel data and outputting encoded data. The data encoding system includes a reference pixel generating device which outputs reference pixel data corresponding to the input color pixel data to be encoded; a predictor having a color order table which sets the color ranks of color codes for every reference pixel pattern, reads and outputs the color rank of the corresponding color code from the color order table on the basis of the color pixel data to be encoded and its reference pixel data; and an entropy encoding device which converts the color ranking data into encoded data and outputs the encoded data.

Abstract: Image data decompression apparatus and method for receiving data words comprising a first sub-word and a second sub-word, at least some possible values of the first sub-word specifying a run of at least m instances of a predetermined data value, corresponding second sub-words specifying a number of instances of the predetermined data value in a range from at least m instances. The apparatus includes a first decoder for decoding the first sub-words to detect whether a current first sub-word specifies a run of at least m instances of the predetermined value, and a second decoder for decoding the second sub-words to generate output decoded data.

Abstract: A method and system of compressing digital image data organized as successive data groups of bits, the contents of which are values of pixels of an image, by checking a first condition of whether a first data group has the same contents as one or more following data groups. If the first condition is satisfied, then the data groups are replaced, in a compression step, by a compression code representing these data groups. Otherwise, in a copying step, only the first data group is replaced by a code consisting of the contents of the data group. These steps are repeated for the next data groups. The method also adds an identification code for characterizing the nature of the code, but only when the compression step is carried out. A related method and system of decompression checks a first condition of whether an identification code is included in the compression codes. If the condition is satisfied, then decompression takes place, else copying takes place.

Abstract: An image signal compressing device having a spatial frequency data amount setting unit and a quantization table generation unit. A set data amount is set in the spatial frequency data amount setting unit for each of a plurality of spatial frequencies based on a preset total data amount and a discrete cosine transformation (DCT) data statistical amount corresponding to quantized DCT coefficients using a quantization table in which all quantization coefficients are "1". An amount of encoded data obtained using a predetermined quantization coefficient is estimated in the quantization table generation unit. The predetermined quantization coefficient is adopted as a resultant quantization coefficient of the quantization table when the estimated data is not greater than the set data amount set in the spatial frequency data amount setting unit.

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: Characters that are not among those recognized for use in page messages are encoded using a subset of the recognized printable characters to enable the data comprising a page object to be transmitted over a paging channel. In one preferred form of the invention, a subset of the recognized printable characters are designated as encoding characters for use in encoding data that includes characters not among the recognized printable character set. Further, each time that one of the encoding characters occurs in the input data, the byte representing that character must also be encoded. To encode the characters, the byte is divided into nibbles. Each nibble is a hexadecimal digit that is encoded using one of the 16 encoding characters. If a byte of the input data repeats more than four times in succession, it is run length encoded (RLE) during the encoding process to compress the encoded data.

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: There is provided a method for detecting horizontal and vertical lines of an encoded run length image to identify cells of the image that are formed by the lines. Initially, the method comprises the steps of filtering excess details, such as text, from the image and grouping a portion of the image for analysis. A top profile of the image is generated and, then, points along the top profile are determined where substantial changes in the profile position occur. A horizontal section of the top profile which corresponds to a line completely visible from the top is then extracted from between the points. By repeating the above steps, each horizontal line of the image is detected and extracted from the image. In addition, in order to detect the vertical lines of the image, the image is simply rotated 90.degree. and processed with the vertical lines being positioned horizontally.

Abstract: An image generation method and an image generation apparatus can execute conversion from edge addresses into dot patterns at a high speed and a low cost. A comparator compares predetermined upper-digit bits of input edge-address information indicating the position of a word of a dot pattern to be output with the value of a word counter for counting the number of words of dot patterns which have been output, and determines if an edge position indicated by the input edge-address information is present within the word currently being processed. A decoder detects the edge position within the word based on predetermined lower-digit bits of the input edge-address information. The detected edge position within the word is held within a flip-flop circuit.