Abstract: A method and device for calculating syndromes used in forward-error-correction codes. To calculate syndromes more quickly using a computer with memory access latency, the polynomial equation C(X) is divided by a generator polynomial G(X) to form a remainder polynomial R(X). The remainder polynomial R(X) is then used to speed the calculation of the syndromes. A method of dividing a Nth order dividend polynomial by a 2R order divisor polynomial is also described. In addition, to further speed the calculation of syndromes, the generating polynomial is split into a number of sub-polynomials G.sub.j (X) to yield a number of remainder sub-polynomials R.sub.j (X) used to calculate the syndromes. Calculation of syndromes using evaluation by Horner's rule and a generalization thereof is also described.

Abstract: A method and device for calculating Cyclical Redundancy Checksums (CRC) used in error-detection codes. To calculate CRCs more quickly using a computer with memory access latency, a frame of data is partitioned into a plurality of sub-frames. A look-up table containing pre-computed CRC values is stored in computer memory and accessed during the CRC calculation of the sub-frames. The CRC of the sub-frames can then be calculated and combined to form the CRC of the frame of data. To speed the calculation, CRCs of a number of the sub-frames can be calculated simultaneously.

Abstract: A method and device for evaluating polynomial equations with a logic computer. To evaluate the polynomial equation more efficiently using a computer with latent memory accesses, the polynomial is split into a plurality of sub-polynomials. The sub-polynomials can be simultaneously evaluated using Horner's rule. The results of the sub-polynomial evaluations are summed to obtain the evaluation of the polynomial equation. A device and method are described.

Abstract: A method and an apparatus for encoding an image signal. The apparatus includes an acquisition module disposed to receive the image signal. A first processor is coupled to the acquisition module. At least one encoder processor is coupled to the first processor. The at least one encoder processor produces an encoded image signal under control of the first processor. The method includes the steps of converting an input image signal into a predetermined digital format and transferring the digital format image signal to at least one encoder processor. The method further includes the step of applying, at the at least one encoder processor, a hierarchical vector quantization compression algorithm to the digitized image signal. At the next step, a resultant encoded bit stream generated by the application of the algorithm is collected. The method and apparatus of the present invention may be used in conjunction with an ordinary modem to transmit and/or receive audio, video sequences or still images.

Abstract: A dynamically variable anti-aliasing filtering system calculates on a local basis the compression factors (Cf) present in an image that is being mapped from a two-dimensional source image through a three-dimensional space and into a two-dimensional target image, the apparatus implementing a linear equation of the form:Cf=A*X.sub.s +B*Y.sub.s +Cwhere, X.sub.s and Y.sub.s are, respectively, the horizontal and vertical coordinates of pixels in the source image, and A, B and C are precalculated (each field or frame) constants that depend on the transform matrix function F. A total of four compression factors are required, one for control of horizontal luminance filtering, one for control of vertical luminance filtering, one for control of horizontal chrominance filtering and one for control of vertical chrominance filtering. Three dual accumulator circuits are used to implement the linear equation in X.sub.s and Y.sub.s for three different sets of A, B and C.

Abstract: Apparatus for processing a video signal representing distribution of optically-perceptible information over a video raster includes a video combiner for receiving an input video signal and a delayed video signal and combining the input video signal and the delayed video signal to provide an output video signal. A memory receives and temporarily stores the output video signal and provides the delayed video signal, and read/write circuits access the memory so that pixels of the output video signal are spatially translated relative to the video raster when the output video signal is written into and read from the memory.

Abstract: A shaped video having an input key control signal associated therewith is processed by carrying out a first operation on the input key control signal to provide a first processed signal, carrying out a second operation on the first processed signal to provide a second processed signal, and combining the shaped video signal and the second processed signal to provide an output video signal. One of the first and second operations comprises translation. In this manner, a simulated shadow is added to the shaped video signal.

Abstract: A depth-based video combiner that combines two video signals to produce a combined video signal as a function of respective key signals and a priority signal derived from respective depth coefficient signals also combines the respective depth coefficient signals as a function of the respective key signals and the priority signal to produce a combined depth coefficient for the combined video signal to provide smooth depth transitions at intersecting edges between the two video signals. A mix coefficient for the depth coefficient signals is generated from the respective key signals and the priority signal. The mix coefficient signal is used to combine the respective depth coefficient signals to produce the combined depth coefficient signal.

Abstract: Depth-based recursive video effects are generated by including depth information in the recursive loop. A combined depth coefficient signal output from a depth-based video combiner is modified by a recursive key signal from the recursive image output from the recursive loop. The resulting depth coefficient signal may then be blurred when a recursive blur effect is selected by using an appropriate filter corresponding to that used in the luminance and key recursive loops. The recursive depth coefficient signal from the depth recursive loop is used, together with the depth coefficient signal associated with an incoming image, to produce the priority signal used in the depth-based video combiner.

Abstract: An apparatus creates a "rainbow-like" effect in a decaying video afterimage by including a chrominance phase rotator within a recursive video effects loop, so that the hue of the afterimage is recursively altered as it decays. The chrominance phase rotator can be placed anywhere within the recursive loop, and can also be combined with a blurring effect and/or the decay factor multiplication needed for the basic recursive circuit. Several variants of the circuitry for providing chrominance phase rotation are provided; some suitable for processing cosited chrominance components, others suitable for processing noncosited chrominance components. Additional variations conserve the number of parts required at the expense of technical color accuracy by making simplifying assumptions.

Abstract: A Doppler blood velocity measuring device is described which includes anti-aliasing circuitry. The anti-aliasing circuitry is based upon the use of a multigate Doppler unit which receives Doppler shift frequency information from various depth ranges. Thereafter, the Doppler frequencies received are corrected by adding a correction frequency to the perceived Doppler frequency with the correction frequency selected based on the assumption that blood flow velocity cannot change drastically between adjacent depths.