Abstract: The present invention provides a variable-length code decoder for inputting a code data bit string having a predetermined number of code data bits in every decoding cycle and decoding it, which comprises storing means for storing a decoded symbol and a node in a code tree in the next decoding cycle corresponding to each combination of a value of the code data bit string and a node in the code tree, reading means for reading the decoded symbol and the node in the code tree in the next decoding cycle from the storing means in accordance with the code data bit string inputted in a current decoding cycle and the node in the code tree in the current decoding cycle, outputting means for outputting the decoded symbol read by the reading means, and providing means for providing the node in the code tree in the next decoding cycle read by the reading means to the reading means.

Abstract: An image transforming section subjects image data to compression processing. A quantizing section quantizes the transformed data using a quantization width. A variable-length coding section subjects the quantized data to variable-length coding. A code-amount computing section determines a total code amount by accumulating partial code amounts. A control section performs control based on the code amount. An estimating method selecting section adaptively selects a quantization width estimating method. A coded result storage section stores data of a code amount corresponding to the quantization width. First and second quantization width estimating sections have different quantization width estimating methods.

Abstract: In an image forming apparatus, memory capacity necessary for temporarily retaining image data is reduced. A decoding process is carried out by diving image data for one frame into element data for each color component Y, M, C and K. The element data for each color component is stored in the temporary memory. A controller starts conveyance of recording media on the basis of estimation of the completion time of decoding processing by a decoding speed estimator, and controls the recorders for Y, M, C and K to execute the recording process of element data retained in the temporary memory. This results in an image being recorded on the recording medium for each element data retained in the temporary memory, such that the conveyance of the recording media and the supply of data to the recorders for Y, M, C and K are matched, and the data amount to be retained in the temporary memory is reduced.

Abstract: An image coding apparatus wherein an image signal including a locally high signal can be coded efficiently with minimized distortion by adaptively performing quantization for each subblock. An input image signal is divided into a plurality of subband signals by a subband division section. The subband signals from the subband division section are each divided into a plurality of subblocks by a subblock division section. In a classification section, a subband signal is classified, for each of the subblocks from the subblock division section, in terms of a feature parameter of an image, for example, a dynamic range, and a class index is outputted. In a quantization section, a quantizer is changed over for each subblock in response to the class index from the classification section. Each subblock is coded with a necessary minimum number of bits. The bit number is multiplexed with a code. Accordingly, the code can be decoded by referring to the bit number.

Abstract: A variable-length code decoder includes plural barrel shifters, each of which executes shift processing on inputted variable-length code data bit by bit from the 0 bit to (the bit number of a maximum length codeword -1). The barrel shifters, which are in number equal to the bit number of the maximum length codeword, are arranged in parallel connection. Plural storing devices are provided, each of which stores a pair of a decoded symbol and codeword length thereof corresponding to code data. Plural fetching devices are provided, each of which fetches the pair of the decoded symbol and the codeword length thereof in accordance with the code data outputted from each of the barrel shifters. Each of the fetching devices is connected to a respective barrel shifter and storing devices. A selecting device is provided for selecting a predetermined pair from plural pairs of the decoded symbol and the codeword length fetched by the plural fetching devices in an initial decoding process.

Abstract: An auxiliary storage controlling device is able to assure the data transferring rate even when an irregular occurs. The controlling device comprises a plurality of auxiliary storage units each of which stores the same data, a readout system for reading out said data from said plurality of auxiliary storage units simultaneously in response to a readout command, a detecting system for detecting an auxiliary storage unit in which the reading out of said data is finished at the earliest, a selecting system for selecting said data which is read from said detected auxiliary storage unit, an irregular detecting system for detecting an irregular auxiliary storage unit which is still working, and a readout prohibiting system for prohibiting a consecutive readout command against said irregular auxiliary storage unit. Additional features to assure the data transferring rate are also disclosed.

Abstract: An image signal encoding device which includes a code transforming unit. The code transforming unit includes a separation unit which separates mode information from first code data, a locally decoding unit which locally decodes the first code data using a decoding operation corresponding to the mode information and outputs locally decoded pixel block, and a second encoding unit which encodes the locally decoded pixel block using an encoding operation corresponding to the mode information and outputs second code data. According to the image signal encoding device, the first code data is re-encoded into the second code data having a higher compressibility so as to perform efficient data transmission and storage.

Abstract: A one-block extracting section extracts a pixel block from an input image signal. An area judging section calculates characteristic quantities such as variance information, histogram information and dynamic range information, and judges whether the pixel block is photographic or text-like based on the characteristic quantities. A photographic pixel block is coded by a transform coding section, and a text-like pixel block is coded by a block truncation coding section.

Abstract: An image coding device capable of securely controlling a total code amount to a fixed amount in coding image data including a character image region and a natural image region mixed together.

Abstract: A block boundary information analyzing circuit extracts block boundary information from an input image signal. A blocking circuit divides the input image signal into block images while changing block boundary positions based on the block boundary information every time a coding operation is performed. A discrete cosine transform coder codes the respective block images. A block boundary information adding circuit adds boundary information to the coded image information.

Abstract: An image encoding device. The image encoding device divides the image into blocks, analyzes each block, truncates the block and determines an order using approximate points, quantizes the image data along the order determined in the truncation step, an encodes the data. Processing images with parameters along a determined order permits high quality encoded images within a limited amount of data.

Abstract: An input image is divided into blocks each represented by n.times.n matrix X, and then X.sup.T X is calculated. Singular values of X that are positive square roots of eigenvalues of X.sup.T X and first singular vectors that are normalized eigenvectors of X.sup.T X are calculated by, for instance, the Jacobi method. Second singular vectors that are normalized eigenvectors of XX.sup.T are calculated analytically using the singular values and the first singular vectors. The singular values and the first and second singular vectors thus calculated are coded.

Abstract: An image signal analyzing system for analyzing a pattern of an image on the basis of the waveforms of the image signals. The system includes a block extracting section for sampling an image signal and dividing the sampled image signal into input pixel blocks each consisting of m.times.n pixels (m and n are positive integers), a mean value separating section for subtracting a mean value from each pixel in the pixel block, a first analyzing section for analyzing a feature quantity of the direction of the tone variation of a mean-value separated block obtained from the mean value separating section, a second analyzing section for analyzing a feature quantity of the direction of amplitude of the mean-value separated block, and a judging section for judging a feature of waveform of the input pixel block on the basis of the analysis results of the first analyzing section and the second analyzing section.

Abstract: Apparatus for encoding an image signal which is capable of improving the quality of a reproduced image with respect to not only a general image in which electric power is concentrated in low-frequency region coefficients but also an image where the electric power is concentrated in a high-frequency region. The apparatus comprises a blocking device in which a rectangular area in an image is detected from a digital image signal as a pixel block, and is subjected to an orthogonal transform by a converter to obtain a transformed coefficient. In addition, an activity calculator calculates the variance of the image within the block, and electric power to be preserved during encoding is determined by a power-preservation-rate determining device on the basis of the variance determined.

Abstract: An image coding device for coding an input image of multi-level. In the image coding device, an input multi-level image is analyzed by an image analyzing portion, and update information to be used when a probability estimation value is generated is generated by an update value determining portion on the basis of adjoining pixel information as a result of the analysis by the image analyzing portion. Further, a probability estimation value is generated by a probability estimating portion on the basis of the update information generated by the update value determining portion and the result of the analysis by the image analyzing portion, and the input multi-level image is arithmetically coded by a code word generating portion on the basis of the probability estimation value generated by the probability estimating portion.

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

Abstract: An image signal analyzing system capable of accomplishing shape analysis for processing or coding an image with easy, by space division using two orthogonal representative vectors, or by differential representative vectors given by the difference between representative vectors. With such a system, inner products between mean separated blocks produced by a mean separated unit and a differential representative vector set stored in a memory in advance are computed by inner product computing unit disposed into a binary tree shape having n stages. Positive/negative signs expressing resulting inner products in the respective stages of the binary tree computed by the inner product computing unit are held, as indexes, by n index holding means sequentially, and an index representing the shape of input image information is obtained from the n indexes held by the index holding unit.

Abstract: An image coding method by which accurate code amount control can be performed without the necessity of recursive processing.

Abstract: Disclosed is an image signal processing apparatus in which the position of an input image can be corrected easily irrespective of the shape of the input image by use of attribute information obtained from image information. Image information read by an image information reading unit is stored in an image information storage unit, and rectangular blocks are extracted sequentially from the image information by a block extracting unit. Shapes of images in the extracted blocks are analyzed by a block shape analyzing unit, and the analyzed block shapes are stored in a block shape storage unit. An image signal from the image information storage unit is displayed on an image signal display unit, and the analyzed block shapes from the block shape storage unit are displayed on another display unit.

Abstract: An encoding system which prevents deterioration of a picture quality and provides a high encoding efficiency even when the size of a block is increased to enhance an encoding efficiency. An input image which is divided into blocks by a blocking unit, is supplied to a plurality of encoders which perform encoding in different numbers of tone levels respectively. Respective pieces of encoded image information from the respective encoders are supplied in common to a selector. A block classification unit determines the degree of the tone gradient of an input block and then outputs the classification result to the selector. The selector, in accordance with the block classification result, selects one of the respective pieces of the encoded image information and outputs the selected one as selected encoded image information. For example, when the tone varies greatly, there is selected the encoder which has a small number of tone levels and a high resolution.