Abstract: A device for processing images includes a compressing/coding unit which encodes image data including a plurality of color components to produce fixed-length codes, a memory unit which stores therein the codes produced by the compressing/coding unit, a distribution-measurement unit which measures a distribution of the color components concurrently with the encoding of the image data performed by the compressing/coding unit, and a memory-control unit which releases a memory space assigned to part of the codes relating to colors in the memory unit if the distribution-measurement unit detects that the distribution concentrates on a particular color composition, and records data indicative of the particular color composition in the memory unit.

Abstract: The invention relates to AC coding. The phase angle or the duration of pulses are marked by half-periods or periods and are then provided as stages. The aim of the present invention is to flexibly adjust the bandwidths and bit rates. The number of filler elements that are allocated to the active code elements is increased or reduced. Bit rate flexibility is obtained by increasing or reducing the positions or stages or by configuring the code elements of virtual code words in a serial manner in relation to code words for transmitting information, whereby said code elements are arranged in parallel.

Abstract: The present invention efficiently compresses image data, and stores and manages the compressed data. Image data is compressed in tile unit having predetermined pixels and data packing is performed. The compressed data is compared with compressed data of a preceding packet. If these compressed data are different, the packet data is stored in a memory, and an entry address of the compressed data is stored in a packet table. Meanwhile, if the compressed data is equal to the compressed data of the preceding packet, the compressed data is not stored, but an entry address of the compressed data of the preceding packet is stored in a record of interest in the packet table, and a flag indicative of repetition of the preceding address is set in the packet of interest.

Abstract: A method and apparatus for coding and decoding information is described. In one embodiment, the apparatus comprises a memory and decoding hardware. The memory stores run counts and/or skip counts and the decoding hardware decodes a run count and/or a skip count obtained from the memory during decoding.

Abstract: Disclosed herein is a method for decompressing compressed data. First, a table is prepared in which the number of bits, consecutively present to the right of the certain bit and having the same color as the certain bit, is listed. Then, a predetermined number of reference data bits is taken from a reference line. Next, the table is searched with both the reference data bits and a position of an attentional bit in the data bits, in order to detect the number of bits of the same color as the attentional bit which are consecutively present to the right of the attentional bit. Thereafter, a pixel, right away from the attentional bit by a distance equal to the addition of 1 and the detected number of bits, is found as a color-changed pixel on the reference line. The compressed data is decoded based on the position of the found color-changed pixel.

Abstract: The present invention includes a system, method, and article of manufacture for decompressing a bit stream of compressed data representing a plurality of image blocks. This includes a two-step method of processing both a DC code and a plurality of AC codes. With respect to the processing of the AC codes, a plurality of bits of compressed input data relating to the AC codes are first retrieved from the bit stream. A first decoding operation is then executed based on the obtained compressed input data in order to generate first output data. It is then determined whether sufficient space is available for the first output data. If it is determined that there is sufficient space for the first output data, the first output data is outputted. On the other hand, if it is determined that there is insufficient space for the first output data, an alternate second decoding operation is executed in order to generate second output data.

Abstract: Methods, devices and systems for compressing images are provided. One method includes creating halftone mask structures and applying compression coding techniques to arrayed pixels sorted using the halftone mask structures in order to convert an image to a compressed multi-level, halftoned image.

Abstract: A run length compression technique, that raster image processes page elements into a plurality of groups of raster data and analyzes the groups of raster data for a predetermined set of parameters. An assignment of compression states is made in accordance with results of the analysis for characteristics of transparency, constancy of a value for the groups of raster data, or features within the groups that should not be compressed.

Abstract: A method of compressing pixel information is described. The pixel data is received in a data stream and compressed into a compressed data format by identifying a run of consecutive bytes of the data stream based on the similarity of the consecutive data bytes in the data stream. A mode bit of a compression byte is used to indicate whether a run of consecutive bytes is identified. Count bits of the compression byte are used to indicate the number of times the data bytes are repeated and zero counts may be used to indicate particular types of runs, for example, runs to the end of a scan line and the end of an object. Where a pixel byte is represented by 8 bits, the data stream may be compressed in multiples of four bytes at a time. If a pixel is represent by less than 8 bits, the compression method may look for repetitions of similar bytes one byte at a time.

Abstract: To provide an image coding apparatus that can generate a code that can be decoded by a general decoding apparatus while attaining a high coding speed. As a result of processing in a plurality of prediction units 21, a control unit 11 generates a predicted pixel value for a pixel of interest based on a pixel value of a predicting pixel located at a distance from the pixel of interest, the distance being predetermined for each pixel value prediction unit 21, counts, as a run-length for each pixel value prediction unit 21, the number of times that the pixel value of the pixel of interest successively correspond with the predicted pixel value, selects any of pixel value prediction units related to a run-length of one pixel or more, and outputs a code by referring to a predetermined code table with respect to a distance between the pixel of interest and the predicting pixel for the selected pixel value prediction unit 21 and the run-length thereof.

Abstract: A data encoding and decoding system that comprises a composite fixed-variable-length coding process and an offset-difference coding process for improving data compression performance. A composite fixed-variable-length coding process encodes an input data by first comparing the input data to a predetermined threshold, then selecting a coding scheme from two preselected coding schemes and encoding the input data in accordance with the selected coding scheme. The composite fixed-variable-length coding process also generates an identifier to indicate the selected coding scheme to decode the coded output data if a response to comparing the input data with a predetermined threshold differs from a statistically determined response. An offset-difference coding process encodes a paired input data by first determining the greater of the two input data, then calculating the difference between the larger input data and the smaller input data and replacing the larger input data with the calculated difference.

Abstract: The present invention provides a high speed MMR compression processing method by reducing the number of times of repeating a process of finding the positions of changing pixels a1, a2, b1, and b2. According to this method, first, a bit string corresponding to pixel data is obtained from an image. Then, data are sequentially fetched from the bit string byte by byte. Subsequently, a search is made of a table that describes the number of consecutive bits that are arranged to the right of and have the same color as each of bits of each byte of all bit patterns represented by bits included in the fetched 1 byte. Then, the number of consecutive bits, which are arranged to the right of and have the same color as each of bits of each of the fetched bytes, is detected according to the bit patterns represented by bits of the fetched byte. Subsequently, a pixel placed at the position corresponding to the number obtained by adding 1 to the detected number of consecutive bits is determined as a color changing pixel.

Abstract: A system and method that efficiently compresses data sets that contain one or more repetitive data values. Substitute symbols represent repeated data sequences in the compressed data output. Data sequences that terminate with one or more of a particular value are specially processed by storing their substitute symbols separately from the general substitute symbol dictionary so that they are able to be more efficiently accessed. Substitute symbols for contiguous data sequences that consist of those particular values are also stored separately. The preferred embodiment specially processes data sequences that contain data bytes equal to zero.

Abstract: To realize image coding/decoding device that can compress an input multivalued image with high compression efficiency, the following measures are taken. First and second predictors predict the value of a target pixel based upon image data according to respective predetermined methods and respectively generate predicted value data. A run counter compares the image data and the predicted value data and if prediction hits and run continues to a pixel immediately before a count value of the run of the corresponding predictor is incremented by one. If there is no predictor the prediction of which hits and the runs of which continued to a pixel immediately before, the runs are sent to a selector together with the identification number of the predictor as run data. The selector selectively outputs a run value and an identification number or prediction error data from a prediction error calculator and outputs after the selector encodes it (them).

Abstract: Compression apparatus is described that operates to select an optimum compression procedure to apply to received image data. The compression apparatus can be employed in a page printer having a print engine that must be provided with video data at a constant rate in order to avoid a print underrun. The page printer operates to receive print data and to convert the received print data into rasterized page strips. Some or all of these rasteized page strips can then be compressed by the compression apparatus for later conversion to video data. The compression apparatus operates to compress each received rasterized page strip by selecting a compression procedure that results in a compressed strip that will provide optimum print quality while not causing a print underrun and that is below a threshold data size.

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: A plurality of patterns such as half-tone patterns, solid patterns, edge patterns, and verbatim data are losslessly represented in a compressed raster data stream. A pattern selection module selects among the various patterns to provide the best combination of lossless representations according to particular criteria such as storage compactness. Half-tone patterns are compressed by exploiting the characteristics of the half-tone threshold screen used to generate the half-tone image. A half-tone pattern codebook is produced by half-tone screening a calibration image. A packet formatting module packs multiple pattern identifiers and lossless representations into a packet which may be transmitted compactly. Upon receipt, a packet deformatting module unpacks the pattern identifiers and lossless representations from the packet. After deformatting, a pattern decoding module uses the pattern identifier to activate appropriate pattern generation modules.

Abstract: A plurality of patterns such as solid patterns, edge patterns, half-tone patterns, and verbatim data are losslessly represented in a compressed raster data stream. A pattern selection module selects among the various patterns to provide the best combination of lossless representations according to particular criteria such as storage compactness. A packet formatting module packs multiple pattern identifiers and lossless representations into a packet which may be transmitted compactly. Upon receipt, a packet deformatting module unpacks the pattern identifiers and lossless representations from the packet. After deformatting, a pattern decoding module uses the pattern identifier to activate appropriate pattern generation modules. Each pattern generation module regenerates data according to an indicated pattern to recreate the original raster data.

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: The present invention relates to an image processing apparatus, and to realize improved lossless compression of images more efficiently. A first predictor 11 generates a prediction signal P out of peripheral pixel values supplied from a pixel sequence generator 2. A second predictor 12 generates a prediction signal Q out of the peripheral pixel values supplied from the pixel sequence generator 2. An adder 4 subtracts the prediction signal P from the current pixel value to thereby calculate a prediction error signal M. When the prediction signal Q is greater than the prediction signal P, an inverter 14 inverts the polarity of the prediction error signal M to consequently generate a prediction error signal N. And an entropy encoder 5 allocates a code word in accordance with the prediction error signal N generated by the inverter 14.

Abstract: A method of correction for toner misregistration in color printing systems, specifically for run length encoded image data. This method, called “trapping”, usually involves extending the color separations one or more pixels to overlay the edge. The color of the “trap zone” is chosen such that it is nearly imperceptible in the presence of the two initial colors. Our approach assumes the existence of a “trap generator”, which provides a trap color given two input colors.

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: An apparatus is provided that includes data compression logic that is configured to receive a data stream and selectively count consecutive alike n-bit long words of data therein. Then, for each grouping of consecutive alike n-bit long words, the logic substitutes a control word that identifies the value of the alike n-bit long words and the counted number of alike n-bit long words within the grouping. Hence, the number of repeated same valued words can be significantly reduced. In certain implementations, the data stream is associated with a scanned image and the alike n-bit long words are selected from a grouping of image pattern values associated with white regions, black regions, and repeating pattern regions on the scanned page. This application of the invention significantly reduces the amount of data that needs to be buffered, for example, in a printer.

Abstract: An encoder of the present invention includes: G storage sections for storing G groups of data; a selection section for selecting one of H Huffman codebooks having codebook numbers for each of the groups of data; G encoding sections Huffman-encoding the G groups of data by using the selected Huffman codebook; and an encoding section for encoding the codebook number of each Huffman codebook selected. The selection section includes a calculation section for calculating a code length and a control section for selecting one of the Huffman codebooks. When the Huffman codebook selected is an unsigned codebook, a number of bits required for sign information has previously been added to the calculated code length.

Abstract: Apparatus and method for generating parameters used in coding data in a data transmission system. The method determines a number of possible coding parameters to satisfy a target coding gain and selects the best set of parameters that balance the code word length and the error rate. In this manner, a minimum coding gain may be used, which minimizes cross-talk on a transmission link.

Abstract: A method for losslessly transmitting data is provided. The data is separated into two or more portions and the second portion is subtracted from the first portion to find a difference. The first portion and the difference are transmitted, and then the second portion is reconstructed by adding the difference to the first portion. The data may comprise two or more images, with each image being a temporally displaced version of the preceding image. Each image may be divided into multiple areas, where the areas on each image correspond to the areas on the other images. A difference may be obtained by subtracting each area of an image from the corresponding area of the preceding image. The first image may then be transferred as a reference image along with the differences, and each image may be reconstructed by adding each difference to the corresponding area of the previous image.