Abstract: A system providing a guess mechanism for improving the speed of translating effective addresses produced by a processor to real addresses in memory is disclosed wherein a set of Lookaside Tables and logic elements are used along with a set of validity registers and an MRU register to guess at the appropriate real frame index from one of the Tables to be output in the real address in the first cycle of a two cycle operation. The low order bits of the effective address are sent to index the Tables during the first cycle and the high order bits are used during the second cycle for comparison with the set of Table entries selected in the first cycle as containing the real frame index that is output. The selection of the actual real frame index that is output involves a guess using the validity and MRU registers along with indexing of the Tables by a portion of the low order bits.

Abstract: A display system for converting first gray level signals of N bits/dot each, representing 2.sup.N gray levels, to second gray level signals of M bits/dot each, representing 2.sup.M gray levels, where N is an integer larger than or equal to 2 and M is an integer satisfying N>M.gtoreq.1, by separating each of the first gray level signals of N bits into higher M bits and lower N-M bits and respectively using the N-M bit values to select an appropriate table from among 2.sup.N-M tables, each of which stores a distinctive set of P.times.Q modification values satisfying P.times.Q.gtoreq.2.sup.N-M, then respectively adding the M bits and each of the modification values of said selected table to generate P.times.Q second gray level signals, and supplying the resulting second gray level signals to a display device of 2.sup.M gray levels. The first gray level signals may be supplied to a display device of 2.sup.N gray levels having a smaller number of display dots than the display device of 2.sup.M gray levels.

Abstract: An image processing apparatus and method is disclosed for rapidly rotating images through selected angles by first generating each pel row of a scaled version of an original image in response to scaling values determined by the rotation angle selected; then performing horizontal shear and vertical shear operations, in response to values of horizontal and vertical shears determined by the selected rotation angle, and generating addresses in an output image memory into which the first pels of the pel rows of the scaled image are to be stored; in response to the value of vertical shear and the address of the first pel of each respective row, generating respective lines of addresses in the output memory into which all the remaining pels of each respective pel row of the scaled image are to be stored; and finally storing all the pels of the pel rows in the generated addresses of the output image memory.

Abstract: A system and method for maximizing data compression by optimizing model selection during coding of an input stream of data symbols, wherein at least two models are run and compared, and the model with the best coding performance for a given-size segment or block of compressed data is selected such that only its block is used in an output data stream. The best performance is determined by 1) respectively producing comparable-size blocks of compressed data from the input stream with the use of the two, or more, models and 2) selecting the model which compresses the most input data. In the preferred embodiment, respective strings of data are produced with each model from the symbol data and are coded with an adaptive arithmetic coder into the compressed data. Each block of compressed data is started by coding the decision to use the model currently being run and all models start with the arithmetic coder parameters established at the end of the preceding block.

Abstract: A system and method for improving the quality of decoded images, without any cost to compression efficiency, in both progressive still frame and motion video applications wherein the images are coded with intraframe transform based coding techniques, such as Discrete Cosine Transform (DCT) coding. Prediction of the AC components is utilized and operations are performed on the AC coefficient prediction in the decoder portions of the system in combination with a thresholding technique. Input images are subdivided into blocks of pixels, which are changed into blocks of coefficients by forward transform coding resulting in DC coefficients, representative of the average value in a block of pixels, and AC coefficients, representative of harmonic frequencies from the block, whereupon the predicted coefficient values are thresholded and the thresholded coefficient values are added to their corresponding transform coefficient values for the given block.

Abstract: A system for processing image data of a text document in compressed form wherein pel signals of the original image are stored in pel positions in an input image buffer and the pel signals stored in every other pel (EOP) positions in the input buffer are sequentially fetched, along with respective pluralities of neighboring pel signals stored in EOP positions and compressed by adaptive arithmetic compression to generate a first set of compressed data which is stored in a memory. The pel signals stored in remaining pel (RP) positions in the input image buffer are also sequentially fetched, along with respective pluralities of neighboring pel signals, including at least one signal stored in an RP position and a plurality of signals stored in EOP positions, and compressed by adaptive arithmetic compression to generate a second set of compressed data which is stored in a memory.

Abstract: A multiprocessing system is presented having a plurality of processing nodes interconnected together by a communication network, each processing node including a processor, responsive to user software running on the system, and an associated memory module, and capable under user control of dynamically partitioning each memory module into a global storage efficiently accessible by a number of processors connected to the network, and local storage efficiently accessible by its associated processor.

Abstract: A system is described for reformatting halftone data for compression, wherein an original bilevel image is reformatted to produce another bilevel image that allows vertical correlations to be recognized by the compression technique, thus improving compressibility dramatically, with particular suitability for facsimile transmissions. In reformatting it is assumed that a selected halftone frequency H will satisfactorily describe an entire document, and each of successive sets of H consecutive lines are concatenated to form respective single lines. The thus reformatted lines have a clearer halftone periodicity offering greater correlation and permit more efficient coding by well-known standard bilevel compression algorithms (e.g., CCITT G3 (MR) or GF4 (MMR)). For an image with unknown pattern frequency, a technique for readily estimating the frequency for use in reformating the image is described.

Abstract: Apparatus and method for adapting the estimated probability of either the less likely or more likely outcome (event) of a binary decision in a sequence of binary decisions involves the up-dating of the estimated probability in response to the renormalization of an augend A. The augend A changes value with each binary decision, the size of the change depending on which of the binary events has occurred as input. Re-normalization of A occurs when the A value becomes less than a prescribed minimum value AMIN. According to the invention, there may be differing contexts in which binary decisions may occur, each context having a corresponding estimated probability value which is up-dated with binary decisions in the respective context. Also according to the invention, there may be one or more possible next values for an estimated probability in response to a given binary decision event.

Abstract: A method and system for performing a leading 0/1 anticipation (LZA) in parallel with the floating-point addition of two operands (A and B) in a computer to significantly reduce the Addition-Normalization time. A combinational network is used to process appropriate XOR (P), AND (G) and NOR (Z) state signals resulting from the comparison of the bits in corresponding bit positions of the operands (A and B), starting with the most significant bit (MSB) side of the addition. The state of the initial state signal is detected and shift amount signals are produced and counted for each successive state signal detected, as long as the state remains TRUE. When the state becomes NOT TRUE, adjustments are made depending on the initial state and the successive state, and production of the shift amount signals is halted and an adjustment signal is produced. To determine the exponent of the sum of the floating-point addition, the shift amount count is summed with the adjustment signal.

Abstract: Apparatus and method for compressing and de-compressing binary decision data by arithmetic coding and decoding wherein the estimated probability Qe of the less probable of the two decision events, or outcomes, adapts as decisions are successively encoded. To facilitate coding computations, an augend value A for the current number line interval is held to approximate one by renormalizing A whenever it becomes less than a prescribed minimum AMIN. When A is renormalized, the value of Qe is up-dated. The renormalization of A and up-dating of Qe are preferably based on a single-bit test. Also, each Qe value is preferably specified as a 12-bit value having the least significant bit set to 1 and having no more than four other bits set to 1. The number of Qe values in the 1/4 to 1/2 probability range is enhanced to improve coding efficiency.

Abstract: A system is disclosed for arithmetically compressing bi-level data of an image by sampling history pels, which are adjacent pels to a current pel to be processed, and pels so separated from the adjacent pels as to adapt to a period of a dither matrix for a dither image. From the sampled pels it is determined whether the sampled image has a dither dominant image pattern or a text-graphic dominant image pattern and an appropriate signal is generated, a first signal representing that the image has the dither dominant image pattern, a second signal representing that the image has the text-graphic dominant image pattern, and a third signal representing that the image is not classified as either of these image patterns.

Abstract: A graphics processing system has the capability of generating a map of an image in terms of the individual picture elements or pixels from data defining the boundaries of component areas of the image. The disclosed generating system comprises a plurality of paired storage locations, called a convex area table, with each pair of locations being associated with a line of individual picture elements on the image. Processing logic computes display line and displacement values for a component area of the pair of storage locations for the corresponding display line. The stored displacement values can then be used for generating the full pixel map of the image.

Abstract: A data compression/de-compression system includes a first arithmetic coding encoder, characterized by a first set of encoding conventions, which encoder generates a code stream that points to an interval along a number line in response to decision event inputs. The code stream can be adjusted to point to the same interval as code streams generated by one or more other arithmetic coding encoders characterized by encoding conventions differing in some way from those in the first set. In a binary context, optimal hardware encoders increment or decrement the value of the code stream in response to each occurrence of a more probable decision event while optimal software so changes the code stream value for each occurrence of a less likely event. According to the invention, the code streams for optimal hardware encoders and optimal software encoders are made either identical or compatible to enable similar decoding for each.

Abstract: A method for encoding and decoding digital image data, includes the steps of: testing the data for a vertical relationship between adjacent lines of the image; generating directly a reference code word representative of the vertical relationship for each successful test; generating by table lookup a run code word for a stream of data bits of common value for each unsuccessful test whereby a data element representing a number of bits in a code word is stored at a predetermined offset from a table entry for the code word; merging the vertical reference code words and the run code words generated by the above steps to form an encoded data stream; testing the encoded data stream for a reference code; decoding directly the vertical relationship from the reference code for each successful test; decoding by table lookup a run of bits of common value by serial examination of said encoded data stream for each unsuccessful test; and storing data decoded by the above steps in a predetermined relationship.

Abstract: Digital data defining images are stored in a multiplane buffer. The buffer may store plural images by restricting data corresponding to an image or image portion to storage in less than half the bit planes of the buffer. An image is displayed by reading data from the buffer and selectively passing only a portion of the data read to a display. The data defining the images may be converted from facsimile (single bit per pixel) to gray scale format (multiple bits per pel) before being written to the buffer. The conversion relies on a table storing data definitive of the effect, on the image, of a facsimile transition (1/0 ot 0/1) as a function of the location of the transition. Conversion from facsimile to gray scale is effected by examining the facsimile data for data transmission and summing the effect of each of the transitions to convert a segment of facsimile data to gray scale data.A system is also disclosed for rapidly converting an image in run-end form to a reduced-resolution gray-tone image.

Abstract: The method according to the present invention enlarges a binary digital image by a method comprising the steps of: storing the rows of the image as a plurality of run end representations, in which a row is represented as a sequence of values giving the white and black run ends; enlarging each row of the image along the horizontal axis by altering the value of each run end representation to achieve enlargement on the horizontal axis by a factor F1; enlarging the image along the vertical axis by interpolating rows between the lines of the partially enlarged image so as to produce enlargement along the vertical axis by a factor F2; storing the enlarged size image generated by the above steps in run end form. An image enlarged by the method of the present invention may be reduced by the simple technique of dividing the image into blocks of pixels and assigning one pixel in a reduced image for each block of pixels in the larger image.

Abstract: A method for carrying out morphic transformations with minimal memory accesses by using a two step convolving sequence to form an intermediate image. The components of the intermediate image are used in a recursive process to provide the desired final convolution. The word resulting from this convolution is then used to access a morphic transformation table in a second memory access for table hookup. The two step convolution requires a total of only two memory reads and two memory writes.

Abstract: In an image in which some pixels in some rows of an image have values associated therewith, apparatus and method of processing, for subsequent entropy coding or decoding, graylevel data for the remaining pixels in the image.

Abstract: An improved printing member for use in a system wherein a current source, in combination with a resistive ribbon, produces heating in selected areas of the ribbon for effecting the formation of a printing pattern on the printing member, which member is composed of a first layer, having a predetermined melting temperature, and a heat-conducting layer which adheres to the first layer below its predetermined melting temperature and which adheres to said resistive ribbon at temperatures above said predetermined melting temperature, such that, when the second layer is heated to a temperature level above the predetermined melting temperature in selected areas forming a pattern to be printed, the selected areas will adhere to the resistive ribbon and release from the first layer.