Abstract: A system and method that introduces intentional errors into a compression scheme for images. The intentionally introduced errors along with error correction processing enable improved low entropy encoding of the images. The errors transmitted over a communication channel are reduced by adding an error correction code to the transmitted data. In an exemplary system and method, an image is blocked to create a plurality of pixel blocks. The blocked image is transform coded and quantized to quantize transform coefficients. The image is low entropy coded. The image is error correction coded to improve communication through a communication channel that introduces errors. The entropy coded coefficients are truncated to introduce intentional errors into the image that is communicated over a communication channel. Upon reception, blocks of the received image are expanded to produce entropy coded coefficients, which are error correction decoded.

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 decoding variable length coded DVC data and methods of operating the same result in a variable length decoder engine that receives video frames having a plurality of digital interchange format (DIF) sequences and provides contiguous decoded run-length amp pairs. The variable length decode engine comprises a concatenation engine configured to contiguously format a plurality of DIF blocks of a DIF sequence to provide contiguous DCT blocks. The concatenation engine has a controller that utilizes several passes capable of running simultaneously to return the DIF blocks coded according to IEC standards to their original variable length sequences. A run-length amp pair generator coupled to the concatenation engine configured to decode the contiguous DCT blocks to provide the run-length amp pairs.

Abstract: An apparatus and method for obtaining scalability of a video object (VO) whose position and/or size changes with time. The position of an upper layer picture and that of a lower layer picture in an absolute coordinate system are determined so that corresponding pixels in an enlarged picture and in the upper layer picture may be arranged at the same positions in the absolute coordinate system.

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 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 and apparatus for manipulating digitized images stored as variable length encoded bitstreams such as JPEG format in a manner that reduces memory and processor resource requirements. A prescan means sequentially decompresses the bitstream to identify the location of encoded pixel image areas. Designated ones of these locations are recorded or stored in a prescan table. After the prescan operation has been performed on the image, image manipulations such as rotating, cropping, and zooming can be performed on a selected portion of the image by directly accessing only the encoded pixel image areas to be manipulated, without the need to sequentially decode and store all the encoded image areas in order to locate the ones of interest.

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: Huffman encoding, particularly from a packed data format, is simplified by using two different table formats depending on code length. Huffman tables are also reduced in size thereby. Decoding is performed in reduced time by testing for the length of valid Huffman codes in a compressed data stream and using an offset corresponding to a test criterion yielding a particular test result to provide a direct index into Huffman table symbol values while greatly reducing the size of look-up tables used for such a purpose.

Abstract: The invention provides a picture data decompression apparatus which reduces the time required for decompression of picture data and operates at a high speed. The picture data decompression apparatus includes a module switching section for extracting code patterns in units of n bits the compressed picture data, m decoding and dequantization modules, and an inverse orthogonal transform section for inverse orthogonal transforming decoded and dequantized data from the m decoding and dequantization means. Each of the decoding and dequantization modules decodes and dequantizes, from a code pattern in units of n bits extracted by the module switching section, only a predetermined variable length code of a single unique code pattern of n bits from among m different predetermined patterns.

Abstract: A coded data length detection apparatus and method capable of detecting a coded data length at a high accuracy at a high speed, wherein original image data input to an image compression and coding circuit is processed by DCT at a DCT unit and quantized at a quantizer, quantization coefficients at this time is obtained by switching first set of scale coefficients and second set of scale coefficients in a lattice pattern in units of MCU of an image in scale coefficients switch, Huffman coding is performed on a quantized result at a Huffman coding unit, a data length is counted at a first compressed data length counter or a second compressed data length counter, and the counted data lengths is respectively multiplied by 2× at a first double multiplier or a second double multiplier to find a data length at the time of encoding the entire image by the respective scale factors.

Abstract: An image compression system includes a vectorizer and a hierarchical vector quantization table that outputs embedded code. The vectorizer converts an image into image vectors representing respective blocks of image pixels. The table provides computation-free transformation and compression of the image vectors. Table design can be divided into codebook design and fill-in procedures for each stage. Codebook design for the preliminary stages uses a splitting generalized Lloyd algorithm (LBG/GLA) using a perceptually weighted distortion measure. Codebook design for the final stage uses a greedily-grown and then entropy-pruned tree-structure variation of GLA with an entropy-constrained distortion measure. Table fill-in for all stages uses an unweighted proximity measure for assigning inputs to codebook vectors. Transformations and compression are fast because they are computation free. The hierarchical, multi-stage, character of the table allow it to operate with low memory requirements.

Abstract: Raster images are highly compressed by first reordering the data. Next the reordered data is indexed to encode any and all predicted runs and literal runs. Each piece of the present line of the raster image is compared to a previous line. If there is a match, then the present piece is a predicted run and indexed accordingly. If there is no match, then the present piece is a literal run and indexed accordingly. A predicted run can have a minimum run length of one piece, and a maximum run length of the image width in pieces divided by the number of strings. The same is true for literal runs. The index strings are then compressed using a lossless compression method such as Huffman encoding. If Huffman encoding is used, the Huffman tables are predefined and known to both the compressor and decompressor. As the compressor compressed the index strings, the Huffman tables are adapted. The decompressor is notified by the compressor when the adapted tables are to be used.

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: 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 variable-length encode/decode processor includes a central processing unit and an instruction buffer and a getbits processing engine coupled to the central processing unit. Such a processor can be used to encode data as variable-length symbols or to decode variable-length symbols such as those found in an MPEG bitstream.

Abstract: To compress images using transition information of adjacent pixels, index transition patterns of two adjacent pixels in the horizontal scanning direction of an image are computed and arranged in order of appearance frequency, then patterns within the upper four appearance frequencies are selected to create a reference table. Then, with reference to the created reference table, image data are encoded. When decoding the encoded data, at first data from both the reference table and the color look-up table is inputted and stored in the table 50 and the color look-up table 53. After this, the first data of the subsequent input data is supplied to both the color look-up table 53 and the delay circuit 51 by changing over the connection of the switch 52. Subsequent data is supplied to the table 50. The table 50 decodes the data to original image data with reference to the data and the output from the delay circuit 51.

Abstract: A raster/block conversion circuit 12 divides an input image from an image input unit 11 into blocks. An image characteristic determination circuit 13 calculates the image characteristic for each block, thereby determining the image type for each block. Based on the determination result of the image characteristic determination circuit 13, a switch circuit 18 adaptively switches an ADCT coding circuit 14 adopting a variable-length irreversible coding technique and an intrablock quad coding circuit 15, an intrablock binary coding circuit 16, and a block run length coding circuit 17 adopting a fixed-length irreversible coding technique.

Abstract: In an image data conversion device which converts image data comprising pixels of M columns (M is a positive integer) in the horizontal direction * N rows N is a positive integer) in the vertical direction, the image data are the first one dimensional data wherein pixels for M columns continuing in the horizontal direction are repeated N times in sequence in the vertical direction, and the image data conversion device includes a line memory for storing the first one dimensional data, a detection circuit connected to the line memory for detecting the pixel number M in the horizontal direction of the first one dimensional data and a conversion circuit for converting the first one dimensional data into the second one dimensional data wherein each pixel of the first one dimensional data is arranged in the order in accordance with M.

Abstract: A data decoding apparatus having a simple circuit configuration and processing data at a high speed by detecting and deleting a marker code by a simple circuit at a high speed. A marker remover deletes the marker from a data stream containing the input marker and generates a data stream having 32 bits of fixed length comprised by only data. Also, 4 bits of a marker flag indicating a type and a location of a marker are generated and added to each data. The 32 bits of data are input via a buffer RAM to a Huffman decoder, the restart marker is detected from the marker flag, and the decoding is carried out while appropriately resetting the DC component value based on this. At the decoding, processing for deleting the restart marker in the data string becomes unnecessary, thus the decoded data can be successively output. Also, the circuit configuration becomes simple too.

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 VLD decodes MPEG2 data so as to generate RUN and Level therefrom. A multiplication unit multiplies target data to be added to the Level, and sends a multiplied result to an adder. The adder adds the target data to the Level. The VLC codes the MPEG2 data, using the RUN and the Level to which the target data is added. The selector compares the data length of the MPEG2 data which has been decoded by the VLC with the data length of the original MPEG2 data. If those data lengths coincide with each other, the selector selects the MPEG2 data output by the VLC. On the contrary, if those data lengths do not coincide with each other, the selector selects and outputs the original MPEG2 data. A counter counts the number of times the selector has done the selection, while another counts the number of times the selector has selected the data output by the VLC. The comparator compares the counted values of both of the counters, and adjusts the insertion degree based on a result of the comparison.

Abstract: A pipeline video decoder and decompression system handles a plurality of separately encoded bit streams arranged as a single serial bit stream of digital bits and having separately encoded pairs of control codes and corresponding data carried in the serial bit stream. The pipeline system employs a plurality of interconnected stages to decode and decompress the single bit stream, including a start code detector. When in a search mode, the start code detector searches for a specific start code corresponding to one of multiple compression standards. The start code detector responding to the single serial bit stream generates control tokens and data tokens. A respective one of the tokens includes a plurality of data words. Each data word has an extension bit which indicates a presence of additional words therein. The data words are thereby unlimited in number.

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: 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: In a variable length code decoder, code information containing a variable length code composed of a variable length bit numerical part and a 1-bit sign part is supplied to a decoding unit. A numerical part decoding unit decodes the numerical part and outputs numerical data. A code length decoding unit decodes code length of the variable length code, and outputs a value one less than the code length as code length information. A shift unit shifts the code information by the value of the code length information and outputs the sign part as sign data. Since a sign part decoding circuit having logic gates is not needed, circuit size can be reduced.

Abstract: An encoding/decoding method and apparatus encodes an input data stream for compression purposes, and decodes the compressed data stream for use. The encoding process identifies trends in the data stream, and stores information about the trends in an encoded block. The trends may include runs, in which sequential, corresponding gropus in the data stream have constant values. The trends may also include ramps, where sequential, corresponging components in the data stream increase or decrease by a linear value. An encoded block may also be provided to transfer raw data. The encoded blocks do not store type information describing the type of the component associated with the block. Rather, the decoder infers the type of the components associated with the encoded block according to an original order of components in the data stream, the order of the encoded block in the sequence of encoded blocks and a number of the corresponding components encoded by each of the preceding encoded blocks.

Abstract: An image format for storing digital images within a baseline DCT compatible bitstream comprises entropy coded image data, a first application marker storing a first data value using a first encoding method to convey a first information value related to the image, and a second application marker storing a second data value using a second encoding method to convey the same said first information value related to the image. More specifically, the first application marker uses TIFF tags within an Exif application marker and the second application marker uses a FlashPix compatible structured storage stream, while the entropy coded data includes restart markers to define tile boundaries within the entropy coded image data.

Abstract: A variable length encoding unit includes a run-length converter, a table memory, and a variable length encoder. The run-length converter converts block data consisting of a plurality of image signals into a zero-run number and a level value in accordance with a scanning sequence. The table memory stores a VLC (variable length code) and VLC length at an address corresponding to the zero-run number and level value. The variable length encoder reads the VLC and the VLC length from the table memory in response to the zero-run number and level value converted by the run-length converter, and carries out the variable length coding by cutting the VLC from the read data in accordance with the VLC length. The variable length coding unit can flexibly handle various types of variable length coding/decoding schemes including international standard coding methods without insisting on its unique variable length coding.

Abstract: System and method using a competitive process to create an optimized set of variable length bit codes to encode one, two or three dimensional data and a high speed redundant lookup table for decoding the resulting representation in real time. The encoding phase consists of multiple passes through the unencoded data to determine the overall best code set for the given data. The primitives used to encode the data may be any mix of operations that captures the redundancy of the raw data. For graphic applications, specific colors and patterns copied from previously occurring data yield sufficiently high compression ratios, but any likely candidates for high frequency occurrence may be added to the mix. The encoding algorithm will ignore any non-optimal operations and assign them no space in the code set.

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: The present invention relates to an apparatus and a method for vector descriptor representation and multimedia data retrieval, which can quantize a plurality of feature values described by a vector descriptor respectively, represent the quantized feature values in the form of bit or orthogonally transform the quantized bector feature values, and rearrange the feature values represented in the form of bit from the highest bit to the lowest bit or rearrange the transformed coefficient from low frequency to high frequency to represent the vector descriptor hierarchically.

Abstract: A variable length code decoder for MPEG (Motion Picture Expert Group) includes a barrel shifter for outputting the bit stream being decoded, a register for storing the output data of the barrel shifter, a finite state machine for parsing the output data of the barrel shifter and determining whether the data is an ordinary data or a more than 16-bit data, and outputs resultant control signals, a multiplexer for selectively outputting the output data of the barrel shifter or the register based on the control signal, and a decoding units for decoding a variable length code, a header code of a MPEG2 syntax from the output of the multiplexer in accordance with the control signal of the finite state machine. The variable length code decoder obtains a data throughput rate equivalent to the using of 32-bit data path.

Abstract: A method and apparatus for efficient image encoding in a predictive coding or other error image based image compression scheme, a pseudo-fixed length code is employed to convert certain calculated error values into codewords. The code is pseudo-fixed length since the length of codewords is fixed for a particular range of values and then increased for the next range. The length of codewords is not needed in decoding by choosing prefixes that uniquely distinguish codewords when packed together. As a result, efficient and quick image encoding/decoding is made possible.

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 present invention relates to a method and an apparatus (1158, 1171-1173, 1180-1184, 1188) for decoding blocks of data encoded using a plurality of variable-length code words. Preferably, the encoding used is Huffman coding. The blocks also comprise fixed-length, not-encoded fields and variable-length, not-encoded bit fields. The code words are interleaved with the variable-length, not-encoded bit fields. The apparatus (1158, 1171-1173, 1180-1184, 1188) includes a preprocessing logic unit for removing the fixed-length, not-encoded fields. The preprocessing logic unit outputs the variable-length code words interleaved with the variable-length, not-encoded bit fields, as well as signals indicating positions of the fixed-length, not-encoded fields in the data blocks. The apparatus (1158, 1171-1173, 1180-1184, 1188) also includes a circuit that synchronously passes the position-indicating signals to an output of the apparatus with the data being decoded.

Abstract: This invention relates to compression of prediction error in motion compensated video coding schemes. Prediction frame and motion vectors are used to extract useful information about the properties of the prediction error signal, e.g. its location, directionality, etc. This information does not need to be transmitted because the decoder of the proposed system includes means to extract this information. Information extracted by the encoder and decoder is used to adapt prediction error coding scheme which gives substantial bitrate reductions.

Abstract: A method of compressing media content in which a first predetermined portion of a media content is compressed using a first data-based compression algorithm and inserted into a first portion of a data frame. A second predetermined portion of the media content is compressed using a second data-based compression algorithm and is inserted into a second portion of the data frame. The second predetermined portion of the media content is different from the first predetermined portion of the media content, and the second data-based compression algorithm is different from the first data-based compression algorithm. At least one of the first and second data-based compression algorithms is a private data-based compression algorithm. A plurality of data frames are generated and are made available for distribution, for example, by transmission over a computer network, such as the Internet.

Abstract: Entered symbols are converted by a code ID table to code IDs numbered in order of increasing code length. Code IDs outputted by the code ID table are replaced by means of an ID conversion table, after which the outputted codes are delivered to a code table and to a code-length table. A Huffman code outputted by the code table is packed by a packer based upon a Huffman code length outputted by a code-length table. In accordance with the local occurrence probability of entered codes, the ID conversion table 103 is updated per prescribed number of symbols. Accordingly, the correspondence between Huffman codes and symbols is altered dynamically and it is possible to prevent a decline in the efficiency of encoding of data in which there is a dynamic variation in the probability distribution (occurrence probability) of symbols.

Abstract: A method and apparatus for performing video compression and decompression using dynamic quantization and/or encoding. According to one aspect of the compression method, an image is recursively filtered into its constituent components each represented by a matrix of coefficients. Next, the level of correlation of a first of the matrices of coefficients is determined. Based on the level of correlation of this first coefficient matrix, one of a first quantization technique and a second quantization technique is selected. The first coefficient matrix is then quantized using the selected quantization technique. According to another aspect of the compression method, an image is digitally filtered into its constituent components, each represented by a matrix of coefficients. At least certain matrices are quantized to generated a first quantized matrix.

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: An A/V signal pickup unit receives an audio digital data stream. A CPU carries out a decode process, and adds tag data indicating the attribute of audio sample data to provide the same to an audio signal converter unit. The audio signal converter unit controls the timing of the output operation of sample data according to the tag data.

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: 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: 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: There is disclosed an image processing apparatus in which variable-length compression is performed, e.g. by orthogonally transforming input image data in units of frames, and quantizing the transformed image data. A quantization coefficient used in coding a last image on the basis of image data quantities of a plurality of frames which have been compressed, is controlled.

Abstract: A novel technique for decoding variable length encoded data in a bit stream such as video data compressed in accordance with JPEG, MPEG, or DV standards is disclosed. The disclosed technique preprocesses the input data to generate a pointer to a variable length code table from the encoded code word, the entry in the variable length table providing the information necessary to decode the code word. Preprocessing of the input data includes encoding leading ones or leading zeros and selecting a subset of bits following the leading ones or zeros. The pointer to the variable length code table is generated from a base value corresponding to the symbol type being decoded. The base values for the symbols being decoded may be stored in a first look up table which may contain multiple entries for one or more of the symbol types, the number of entries corresponding to the number of leading ones or zeros.

Abstract: The invention proposes a digital signal coding method including a step of analysing (E1) the digital signal (IM) into a plurality of frequency sub-band signals distributed according to at least two different frequency bands, at least one first sub-band signal having a lower frequency and at least one second sub-band signal having a higher frequency, characterised in that it includes, for each second sub-band signal, the steps of: dividing (E4) the second sub-band signals into blocks (Bi,n), selecting (E9) blocks to be coded by setting to a predetermined value, according to a selection criterion, coding the blocks selected by setting to the predetermined value.

Abstract: An image coding apparatus and method efficiently compresses a variety of images by a lossless or near-lossless coding, and an image decoding apparatus and method decodes code data encoded by the image coding apparatus and method. A windowing unit determines peripheral pixel values, which include a coding object pixel value and values of pixels located near the coding object pixel. An approximation unit uses plural approximation methods so as to output decoded pixel candidates, each of which approximates the coding object pixel value based on the values of the nearby pixels by using one of the plural approximation methods. The plural approximation methods can include an interpolation method and a quantization method. A minimum error selector calculates an error between the coding object pixel value and each of the decoded pixel candidates, and outputs a rank of the approximation method that produced the minimum error. A rank/runlength calculator counts the runlength of first ranks and outputs a coding symbol.