Abstract: A method and system for determining a transition model between input pixel samples from which output sample values are calculated based on various relative background and brightness conditions of the input pixel samples. A brightness condition is determined from the input sample values associated with the input pixel samples. A first transition model that preserves a constant luminance is used where the brightness condition is indicative of light isolated pixels and a second transition model that preserves a constant darkness is used where the brightness condition is indicative of dark isolated pixels. The resampling circuit may also use alternative models for other brightness conditions, such as for pixel transitions without any emphasis or alternating pixels. The resampling circuit may also perform modified operations for pixels arranged in a diagonal fashion.

Abstract: The invention provides techniques for secure messages transmission using a public key system to exchange secret keys. A first entity creates public and private keys by generating a product n of two large, randomly chosen prime numbers, and then generating random matrices {A, C}, in the group GL(r,Zn) with a chosen matrix rank r such that AC is not equal to CA, and then generating a matrix B=CAC, and finding a matrix G that commutes with C. Matrices A, B, G and the integers n and r are then published as the public key and matrix C is then kept as the private key. A second entity then obtains the public key and calculates a secret matrix D that commutes with G, and further calculates the matrices K=DBD and E=DAD. The message to be sent is then encrypted using matrix K as the secret key and then sent to the first entity with matrix E. First entity then retrieves secret matrix K using K=CEC and then decrypts the received encrypted message using the retrieved secret matrix K.

Abstract: A system and method for identifying whether sample values of pixel samples in a sample region have two or fewer different sample values represented, such as in graphics data representing text images. Identification is performed by hierarchically dividing the samples of the sample region into sample pairs and comparing the sample values of a first sample pair and a second sample pair to determine if two or fewer sample values are represented by the sample values of the first and second sample pairs. Where two or fewer levels are represented by the sample values of the samples, a tally value is generated and the first and second sample values are recorded. The recorded sample values are compared to the sample values of another sample pair to determine if two or fewer values are represented therein. If so, a new tally value is generated and the sample values are recorded.

Abstract: A method is comprised of inputting a comparand word to a plurality of hash circuits, each hash circuit being responsive to a different portion of the comparand word. The hash circuits output a hash signal which is used to enable or precharge portions of a CAM. The comparand word is also input to the CAM. The CAM compares the comparand word in the precharged portions of the CAM and outputs information responsive to the comparing step. When used to process Internet addresses, the information output may be port information or an index from which port information may be located. A circuit is also disclosed as is a method of initializing the circuit.

Abstract: A resampling circuit and method where input sample values for samples arranged along a row of a source image are received by a row resampling circuit. The row resampling circuit calculates row output values which are provided to a column resampling circuit that calculates output sample values therefrom. The column resampling circuit includes a shift register that receives the row output values and shifts the row output values through the shift register as the row output samples are calculated. The shift register has a plurality of evenly spaced sample output terminals from which the row output values are sampled by an interpolation circuit for calculation of the output sample values.

Abstract: Asymmetric finite impulse response (FIR) filters are used to estimate gradients for re-sampling models used in image resizing. Better than conventional 3-tap symmetric FIR filters, these filters provide good edge and extended-frequency responses with good narrow peak sharpening characteristics. These filters emphasize accurate edge handling, where gradients are steepest, over accurate peak handling, where gradients are shallowest. This results in superior zone-plate test signals and better resized image quality.

Abstract: An economical method of detecting and suppressing ringing artifacts during digital image resizing is presented. The economical method substitutes costly division calculations with cost effective comparator operations. The method also includes improved image sharpening when up-sampling an image.

Abstract: Systems and methods are provided for writing code to access data arrays. One aspect provides a method of accessing a memory array. Data is provided within a one-dimensional array of allocated memory. A dimensional dynamic overlay is declared from within a block of statements, and the declaration initializes various attributes within an array attribute storage object. The data is accessed from within the block of statements as a dimensional indexed array using the array attribute storage object. Another aspect provides a method of creating and accessing a dimensional dynamic array. A dimensional dynamic array is declared from within a block of statements, and memory storage for the array is dynamically allocated. A dynamic overlay storage object is also provided and its attributes are initialized from the dynamic array declaration. The data is accessed as a dimensional indexed array from within the block of statements using the array attribute storage object.

Abstract: Systems and methods are provided for caching dynamic arrays. According to one aspect, a cache memory device is provided for caching dynamic arrays or dynamic overlays. According to one embodiment, the device includes a plurality of memory cells and at least one register for storing access information to access at least one array stored in the plurality of memory cells. According to another aspect, an electronic system is provided that includes a main memory, a dynamic array cache memory device, a general cache memory device, and a processor. The dynamic array cache memory device is coupled to the main memory and adapted for caching array data. The general cache memory device is coupled to the main memory and is adapted for caching regular data. The processor is coupled to and adapted for communication with the main memory, the general cache memory device, and the dynamic array cache memory device.

Abstract: A method and system for calculating resample output values from input samples and their associated sample values. A resampling circuit calculates a frequency value for a sine-wave model from a sample set of the input samples and determines whether the frequency value is in a frequency range. In the case where the frequency value is in the frequency range, a sinusoidal transition model is determined based on the sample set. However, if the frequency value is outside of the frequency range, a non-sinusoidal model is determined based on the sample set. The resampling circuit then calculates resample output values from the resulting sinusoidal or non-sinusoidal model.

Abstract: A resampling system and method for producing a resampled destination image from a source image by solving coefficients for a cubic polynomial transition model between first and second adjacent source pixels from the sample values of the first and second samples and approximations of the first and second sample gradients at the first and second samples, respectively. Approximations of the first and second color gradients are based on a multiple of first and second color slopes, such as twice the value of the color slope. The first color slope is calculated from the sample values of a previous pixel and the first sample and the second sample slope is calculated from the sample values of a subsequent sample and the second sample. The resulting gradient approximations and sample values are used in the cubic transition model to calculate an output sample value for rendering a resampled destination image.

Abstract: A method and system for determining a transition model between input pixel samples from which output sample values are calculated based on various relative background and brightness conditions of the input pixel samples. A brightness condition is determined from the input sample values associated with the input pixel samples. A first transition model that preserves a constant luminance is used where the brightness condition is indicative of light isolated pixels and a second transition model that preserves a constant darkness is used where the brightness condition is indicative of dark isolated pixels. The resampling circuit may also use alternative models for other brightness conditions, such as for pixel transitions without any emphasis or alternating pixels. The resampling circuit may also perform modified operations for pixels arranged in a diagonal fashion.

Abstract: A system and method for identifying whether sample values of pixel samples in a sample region have two or fewer different sample values represented, such as in graphics data representing text images. Identification is performed by hierarchically dividing the samples of the sample region into sample pairs and comparing the sample values of a first sample pair and a second sample pair to determine if two or fewer sample values are represented by the sample values of the first and second sample pairs. Where two or fewer levels are represented by the sample values of the samples, a tally value is generated and the first and second sample values are recorded. The recorded sample values are compared to the sample values of another sample pair to determine if two or fewer values are represented therein. If so, a new tally value is generated and the sample values are recorded.

Abstract: An improved FIR filter based upon squaring is used to self-determine a filter constant equal to the sum-of-squares of the filter coefficients. An input signal is forced to zero for T samples, where T is the number of accumulator cells in an accumulator stage, and at the end of such zero samples the output from the filter is latched as the filter constant for use in filtering the normal input signal. The FIR filter may also be placed in a co-processor mode, using a FIFO register between the input of the FIR filter and a processor bus. A CPU on the bus initiates the co-processor mode and loads data into the FIFO. When the FIFO has data the data is read out and input to the FIR filter. The output of the FIR filter is placed on the processor bus. To determine the values of the filter coefficients loaded in the FIR filter, the data loaded by the CPU is an impulse signal having T−1 zero samples before and after an impulse sample, the output for each sample representing one of the filter coefficients.

Abstract: An improved FIR filter based upon squaring is used to self-determine a filter constant equal to the sum-of-squares of the filter coefficients. An input signal is forced to zero for T samples, where T is the number of accumulator cells in an accumulator stage, and at the end of such zero samples the output from the filter is latched as the filter constant for use in filtering the normal input signal. The FIR filter may also be placed in a co-processor mode, using a FIFO register between the input of the FIR filter and a processor bus. A CPU on the bus initiates the co-processor mode and loads data into the FIFO. When the FIFO has data the data is read out and input to the FIR filter. The output of the FIR filter is placed on the processor bus. To determine the values of the filter coefficients loaded in the FIR filter, the data loaded by the CPU is an impulse signal having T−1 zero samples before and after an impulse sample, the output for each sample representing one of the filter coefficients.

Abstract: A digital finite impulse response (FIR) filter for compensation of Nyquist slope in a pseudo-synchronous demodulator has a plurality of individual FIR filters coupled in series, having a bandpass filtered intermediate frequency video signal as an input and providing a broadband video signal as an output. The individual FIR filter amplitude responses represent each product term of the following polynomial:A(.omega.)=2(1+x)(1+x.sup.2) . . . (1+x.sup.2 (F-1))where F is the number of individual FIR filters in the series and x=(.omega..sub.m -.omega.)/.omega..sub.t, .omega..sub.m being the modulation frequency and .omega..sub.t being a deviation frequency.

Abstract: A method of encoded communication in which a receiver generates a receiver public key by looking up a monitoring authority public key, multiplying four prime numbers, and encoding the identities of two of the prime numbers with the monitoring authority public key. The receiver communicates the public key to a sender, who creates a message, encodes it with the receiver public key, and transmits it to the receiver. The receiver then decodes the encoded message with the four prime numbers. The monitoring authority may decode the two prime numbers of the receiver's key, and factorize the product of the remaining primes. An unauthorized party would be faced with the much more difficult or impossible task of factorizing the original product of the four primes.

Abstract: A method of encrypted communication including creating a message and looking up a public key of a recipient. Then, encoding the message via a first encoding process using a first portion of the public key to generated an intermediate encoded message. The intermediate encoded message is encoded via a second encoding process using a second portion of the public key to generate a final encoded message. Then, the final encoded message is sent to a recipient. The public key may have a first key portion, a second key portion, and a third key portion, with the third key portion containing the encoded identity of a data element needed to decode a message encoded with the second key portion. The third key portion is encoded with the public key of a monitoring authority to enable the monitoring authority to more readily decode transmitted messages.

Abstract: A FIR filter for programmable decimation by powers of two has an input coupled to receive an input signal and an output coupled to the input. The FIR filter uses context registers, where the number of contexts per context register is equal to the maximum desired decimation power m. An output context register coupled to provide the output simultaneously contains all of the decimation output results, the desired decimation result being selected as one of the output contexts. A cascade of timing circuits in response to an initial clock signal and an initial valid signal at one-half the frequency of the initial clock signal provide timing signals for storing the decimation results as separate contexts in each context register. At any time any desired decimation result is available for output.

Abstract: Block matching for picture motion estimation uses Gray codes, and preferably a new Hamming-2 Gray code where the bit pattern changes by only one bit for each step in the Gray code count sequence with the additional condition that all other codes are at least two bits different if not adjacent in the count sequence. The pixels for a reference block from a first picture frame and the pixels for a corresponding block within a search area of the next picture frame are each quantized and then converted to an appropriate Gray code. The Gray codes for corresponding pixels are compared to determine whether they are equal or adjacent to each other. If there is adjacency or equality a match signal is generated for that pixel which is tallied. The total tally for each reference block position within the search area is determined, with the maximum tally indicating a match between blocks from which picture motion estimation may be determined.