An enhancement to a standard lossy image compression technique wherein a single set of side information is provided to allow decompression of the compressed file. Certain portions of the image are selected (either by the user or automatically) for more compression than other portions of the image. A particular embodiment is implemented for use with the JPEG image compression technique. JPEG calls for subdividing the image into blocks, transforming the array of pixel values in each block according to a discrete cosine transform (DCT) so as to generate a plurality of coefficients, quantizing the coefficients for each block, and entropy encoding the quantized coefficients for each block. Techniques for increasing the compression ratio include subjecting each selected block to a low pass filtering operation prior to the transform, subjecting the coefficients for each selected block to a thresholding operation before the quantizing step, subjecting the coefficients for each selected block to a downward weighting operation before encoding them, or, where the entropy encoding uses Huffman codes, mapping coefficients to adjacent shorter codes.

Image compression technique with regionally selective compression ratio

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. A decision coding parameter of preferably six bits indicates the sense of the more probable symbol (MPS) in one bit and identifies a corresponding Qe value with the remaining five bits. In addition to probability adaptation, the present invention discloses an allocation of bits in a code stream register in which preferably two spacer bits are inserted between a next byte portion (which contains a byte of data en route to a buffer) and a fractional portion which may be involved in further computation. With the two spacer bits, any code greater than or equal to Hex `CO` which follows a Hex `FF` byte is illegal for data and therefore provides for an escape from the code stream. The two spacer bits also reduce the number of stuff bits inserted to account for carry or borrow propagation. Encoding and decoding can be performed interchangeably by hardware or software which feature differing coding conventions.

Arithmetic coding encoder and decoder system

The present invention relates to computer apparatus and methodology for adapting the value of a probability of the occurrence of a first of two binary symbols which includes (a) maintaining a count of the number k of occurrences of the first symbol; (b) maintaining a total count of the number n of occurrences of all symbols; (c) selecting confidence limits for the probability; and (d) when the probability is outside the confidence limits, effectuating a revision in the value of the probability directed toward restoring confidence in the probability value The number of allowed probabilities is, optionally, less than the total number of possible probabilities given the probability precision Moreover, an approximation is employed which limits the number of probabilities to which a current probability can be changed, thereby enabling the probability adaptation to be implemented as a deterministic finite state machine

Probability adaptation for arithmetic coders

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. Identical or compatible code streams are obtained from encoders having different event sequence or symbol ordering along intervals on the number line. Moreover, various hardware and software decoders--with respective symbol ordering and other conventions--can be used in conjunction with encoders having respective conventions, wherein each decoder retrieves the same sequence of decisions for a code stream pointing to a given interval. In both encoding and decoding, the present invention overcomes finite precision problems of carry propagation and borrow propagation by handling data in bytes and bit stuffing at byte boundaries and by pre-borrowing as required.

Arithmetic coding for data compression/de-compression by selectively employed, diverse arithmetic coding encoders and decoders

Disclosed is a remote management system for coupling a series of remote domain servers, file/print servers, headless servers, network appliances, serial IT equipment, switches, routers, firewalls, security interfaces, application servers, load balancers, and environmental controls to one or more user workstations allowing for selective access of the remote devices. The remote devices are all connected to a remote management unit (109) which interfaces each user workstation (101) to the remote devices (115a, 115b). The power supply (117) of each remote device is similarly connected to the remote management unit through a controllable power supply (118). An option menu containing a list of all of the remote devices allows a user to select and operate any of the remote devices from the workstation. The option menu is also utilized to selectively control the power to the remote devices, servers, and computers.

Remote network management system

An apparatus for ensuring continuous flow through a pipeline processor as it relates to the serial decoding of FIFO Rissanen/Langdon arithmetic string code of binary sources. The pipeline decoder includes a processor (11, 23) and a finite state machine (21, FSM) in interactive signal relation. The processor generates output binary source signals (18), status signals (WASMPS, 31) and K component/K candidate next integer-valued control parameters (L0, k0; L1, k1; 25). These signals and parameters are generated in response to the concurrent application of one bit from successive arithmetic code bits, a K component present integer-value control parameter (52) and K component vector representation (T, TA) of the present internal state (51) of the associated finite state machine (FSM). The FSM makes a K-way selection from K candidate next internal states and K candidate next control parameters. This selection uses no more than K2 +K computations. The selected signals are then applied to the processor in a predetermined displaced time relation to the present signals in the processor. As a consequence, this system takes advantage of the multi-state or "memory" capability of an FSM in order to control the inter-symbol influence and facilitate synchronous multi-stage pipeline decoding.

Method and means for pipeline decoding of the high to low order pairwise combined digits of a decodable set of relatively shifted finite number of strings

Langdon

Papers

Method and means for pipeline decoding of the high to low order pairwise combined digits of a decodable set of relatively shifted finite number of strings