Abstract: Phantom raster scanning of an image memory, in which the image is stored in compacted form, is made possible by introducing offsets in strictly spatial coordinates, rather than in time coordinates parallelling a particular spatial coordinate system.

Abstract: Orthogonal Cartesian coordinates descriptive of the raster scanning of a television display screen are generated at a programmable skew angle to the Cartesian coordinates of an image stored in memory. Each of these generated coordinates has a number of more significant bits used to generate the column and row addresses for that memory, four spatially adjacent storage location of which are read from for developing each sample of video signal describing a rotated television image. Each of these generated coordinates has a number of less significant bits affording resolution higher than that with which the memory can be addressed, which are used for calculation of each video sample by two-dimensional interpolation between the read-outs from the four locations in memory. To avoid aliasing as the image is rotated, the digital video to be stored in memory is processed using two-dimensional spatial-frequency low-pass filters to reduce resolution in directions other than horizontal and vertical.

Abstract: The calculation of r.sup.2 =x.sup.2 +y.sup.2, where x and y are the Cartesian coordinates of a raster-scanned space, is carried forward by accumulation of 2x+1 and 2y+1 terms. A read-only memory can then be used for table look-up of r, the radial coordinate of raster scan in polar coordinates.

Abstract: A multichannel sampled system uses a single set of steering bits to reconstruct deleted samples from all channels. The steering bits can be derived from the channel having the greatest bandwidth or amplitude, or by majority voting logic operating on steering bits from all channels.

Abstract: A recording format is provided for video record and/or replay systems, which improves the operating performance and facilitates the implementation of many replay features. In this format, each raster of information is divided into at least two interleaved checkerboard pixel patterns and the pixels for each checkerboard pattern are recorded together and segregated from the pixels for the other checkerboard patterns.

Abstract: In a standard NTSC composite video signal, the peak excursion of the luminance plus chrominance signal for certain saturated colors exceeds the peak excursion of the white-representative luminance alone. When digitized, the signal is subject to quantizing noise. The effective spectial distribution of the quantizing noise is improved by reducing the amplitude of the chrominance signal so that the peak excursion of luminance plus chrominance for saturated colors does not substantially exceed the peak amplitude of white-representative luminance.

Abstract: In a transmission channel, such as a tape recorder, errors in code words usually occur in bursts. Further, it is usually possible to detect only some of the erroneous code words. To conceal undetected erroneous code words, concealment starts before, and continues after, a detected erroneous code word. Thus the undetected erroneous code words in an error burst have a high probability of being concealed.

Abstract: Method and apparatus for replacing defective video information in a video signal line comprises sampling the video signal. Video information from the preceding in-phase pixel and the subsequent in-phase pixel are averaged to form a replacement pixel. Weighting coefficients are generated based upon the amplitude difference between the next adjacent and semi-adjacent pixels having the same subcarrier phase. These weighting coefficients are used to determine the amount of information contribution of the previous and subsequent pixels to arrive at the closest video approximation of the defective pixel. Three times color subcarrier frequency sampling is preferred.

Abstract: A dropout compensator for time spread digital television signals uses either horizontal or vertical averaging to replace a dropped out sample. The choice of direction is made in accordance with whichever direction has the least amount of change around the missing sample or pixel. The circuitry can also be used for chroma invertion when stop or slow motion is to be transmitted or recorded.

Abstract: A TDM scheme has a Y signal that is sampled at 14.32 MHz and every other sample is discarded. The discarded samples are 180.degree. out-of-phase from line-to-line. I and Q signals are sampled at one half this frequency and every other sample is discarded also 180.degree. out-of-phase from line-to-line on a given line. The discarded samples of Q and I are 180.degree. out-of-phase with respect to each other. This allows insertion of the retained I and Q samples into the retained Y samples to allow multiplexing.

Abstract: A dropout compensator includes an estimator for forming continuous estimates of the value of a video signal subject to dropouts. In order to determine the presence of a dropout, the estimated signal is compared with the actual signal to form a difference. When the difference exceeds a predetermined amount, the estimated value is substituted for the actual value.

Abstract: Moviola color picture quality is improved for a record and replay system wherein video sampled at a predetermined multiple of the color subcarrier frequency is recorded with each frame or field being disposed on a set of multiple tracks and with only a portion of the recorded information being intended for replay to reconstruct the color Moviola signal. Only pixel groups relating to entire color subcarrier cycles are recorded on the tracks so that a video signal having proper color information can be readily reconstructed therefrom during the Moviola mode. In one preferred embodiment, sequential color subcarrier cycle pixel groups are recorded on separate tracks with those to be replayed during the Moviola mode on a single track so that Moviola pixel groups on the single track can be repeated in sequence when reconstructing the Moviola picture and thereby supply instantaneously coherent information.

Abstract: An apparatus for providing component-to-composite and vice versa transcodings of a sampled video signal features generating steering bits that indicate which of combinations of surrounding samples of a composite signal has a component that provides the closest match to the corresponding component of an original component video signal. This allows successive transcodings with a minimum of crosstalk between components, e.g., luminance and chrominance.

Abstract: An apparatus reduces quantizing noise by averaging picture information when only low frequency information is present. Thus, high frequency detail is not lost. This is determined by looking at proximate samples to see if their amplitudes are within a selected amount of each other. The averaging typically is of two or four picture samples depending upon how great an area has only low frequencies, but greater numbers of samples can be used.

Abstract: A digital TV system reduces the data rate by transmitting or recording only bytes representing half of the sampled pixels. Steering bits are also transmitted that tell which of the transmitted bytes are the closest match to the untransmitted bytes so the pixels represented by the later can be reconstructed.

Abstract: In television image size altering apparatus of the type wherein pixels relating to a composite video signal are sampled at a synchronous real time rate and wherein the flow of pixel information is coordinated through a memory by a write control and a read control, the composite pixel information is separated into original pixels relating to each basic component of the video signal. Interpolated pixel values are then derived from the original pixel values at an effective rate less than the synchronous rate when compressing the image size and at an effective rate greater than the synchronous rate when expanding the image size. The interpolated pixel values are then combined into new pixel values relating to a new composite video signal and the new pixel values are presented for display at the synchronous rate to alter the size of the television image.