Abstract: A video display device has a scanning standard which is instantaneously adaptively dependent on the presence of movement in the picture. With a 625/50/2:1 input signal, in the absence of motion the standard used is 625/100/2:1. In the presence of motion the standard can remain 625/50/2:1. The video input is applied to aline store (108) and through an attenuator (102) to field stores (104). An appropriate one of the store outputs is selected by a switch (12) in dependence on a movement signal (116). In a preferred alternative, in the presence of motion the standard is altered to 625/50/1:1.

Abstract: A correlation surface is derived by phase correlating two pictures selectively displaced in the X and Y directions. The illustrative surface shows a large peak at zero displacement, corresponding to a stationary background, and a fairly large peak corresponding to a moving object, the X, Y position of the peak indicating the magnitude (pixels per field period) and direction of the motion vector. A set of motion vectors is thus determined and testing is then carried out, on a pixel by pixel basis or pixel block by pixel block basis, to determine which of the motion vectors gives the best match in deriving the second picture from the first. The motion vector thus assigned may be used in temporal interpolation of the pictures.

Abstract: A conventional video recorder comprises electromechanical components, electronic circuits and a control unit with which there are associated both front panel controls and a user remote control unit with a sensor to which signals can be sent from a hand-held remote control unit. In addition to these conventional features an off-air remote controller is provided. This is capable of decoding control signals associated with the television signal and includes an encoder which generates outputs which simulate those from the conventional user remote control unit.

Abstract: An HDTV video signal with 1249 lines per picture is transmitted over a transmission channel designed for 625 lines per picture by transmitting alternate samples of two lines of the 1249 line signal on a single line of the 625 line signal. An HDTV receiver can interpolate to give a 1249 line picture but a 625 line receiver will still receive a signal that is adequately compatible to give a display.

Abstract: At the transmitter a coder includes a motion vector generator providing vectors (MV) describing the movement of individual blocks of pixels. The video signal is 4:1 compressed in bandwidth by pre-filters and a sub-sampling unit to produce a signal (SSH) from which a high-definition image can be re-constructed in the coder and in the decoder. The sampling lattice is shifted in accordance with the motion vectors (MV) which are digitally transmitted along with the compressed bandwidth analogue signal, to enable the samples to be correctly located in the reconstructed image. Poorly correlated moving areas are handled by pure spatial filtering (pre-filter and sub-sampling unit) with reconstruction by spatial interpolation. The two reconstructed signals (RVH and RVL) at the coder are compared in a mode selector with the input video and a switch is set to transmit whichever of the compressed signals (SSH, SSL) gives the best match.

Abstract: A cathode ray tube video display device is adapted to display wide aspect ratio signals by reducing the vertical scanning amplitude of the scanning raster. The scan is collapsed in the vertical direction without reducing the number of lines used to display the active picture, leaving unscanned bands at the top and bottom of the display. The device can change between a normal raster scanning mode and such a collapsed wide screen mode automatically in response to an indicator in the received video signal.

Abstract: A video signal is coded for transmission in a restricted bandwidth by sub-dividing a frame of picture information into a set of constituent blocks, measuring the amount of picture activity in each block, sampling the information in each block at a rate related to the amount of picture activity in that block, and adding to the coded block a supplementary signal indicating the sampling rate used for the block. Thus a decision is made on a block-by-block basis as to whether the block is transmitted with full accuracy or whether it can be adequately reconstructed from the previous frames.

Abstract: In a color television signal the total line length or period and the bandwidth requirement can be conventional, but the active line period is increased to e.g. about 94% of the line period, giving an aspect ratio of about 3:2 instead of 4:3.

Abstract: Conventionally, transmission of television images is performed by Raster scanning. To avoid the problems associated with flyback, and the limiting of Raster scanning to image scanning standards it is proposed to transmit images by scanning along a locus defined by a fractal curve. A Peano curve is particularly suitable. Image resolution may be varied by varying the order of curve used to scan the image. Smoothing of a curve of a given order results in a graceful degradation to a curve of lower order so that the image created by a given order is still recognizable when displayed by a lower or higher order.

Abstract: An amplifying arrangement includes a klystron in which an electron beam interacts with a high frequency signal to produce a modulated amplified signal. The high frequency signal is maintained at a substantially constant amplitude and modulation of the amplified signal is provided by controlling the electron beam current.

Abstract: Missing lines of a video signal are interpolated from the signal on three successive fields by deriving low vertical frequency components solely from the central or current field and the higher vertical frequency components partly from the lines of the current field and partly from the lines of two adjacent fields. The total contribution from the current field is unity and the total contribution from each adjacent field is zero. The circuitry for deriving and combining these components comprises an arrangement of delays, adders, subtractors and multipliers (FIG. 7). The system can be used to generate the missing lines necessary to derive a sequentially scanned video signal from an interlaced scan video signal.

Abstract: Klystrons are inherently non-linear and have an amplification characteristic which is frequency dependent on both signal amplitude and beam current. This may be compensated for by applying suitable correcting signals to a beam controlling electrode of the klystron thereby changing its electron beam current over the whole excursion of a modulating signal. A klystron arrangement in accordance with the invention is particularly suitable for use in a television transmitter, enabling full time modulation to be carried out with a significant improvement in the operating efficiency of the klystron.

Abstract: Video signals (Y,U,V) from a telecine machine are accompanied by a blemish signal (D) (obtained for example by infra-red scanning of a color film) indicating the presence of scratches, dirt etc. This controls a switch (22) to substitute information from another part of the film (e.g. the previous frame, from a frame store 33). To prevent substitution with information also containing blemishes, the blemish signal in respect of the substitute information is made available (flag store 36) to suppress the substitution and switch to an alternative source such as a interpolator (31). The use of a movement detector, (not shown) to suppress substitution from another frame when motion occurs, is also described. The circuitry can be adapted for use in conjunction with a videotape dropout detector.

Abstract: A filter is disclosed for adaptively filtering a PAL or NTSC luminance signal so as to attenuate the high frequency portion of the luminance band, wherein the chrominance information lies, when movement is detected. This reduces cross-color in the reproduced picture. Movement is detected by comparing the undelayed luminance signal with this signal delayed by an integral number of lines corresponding substantially to one field or one picture. The filter may precede a coder or follow a decoder.

Abstract: In a telecine apparatus having a film transport mechanism for moving a film at a nominally constant speed and including a motor driving a capstan around which the film passes, there is a sensor for line-by-line scanning of the film to provide a raster-scanned electrical output signal representative of the film image. Also included is a scan control and a film speed measuring device coupled to the capstan to provide an output representative of the instantaneous film speed. A compensating device connects the output of the film speed measuring device to an input of the scan control such that the scan time of a particular line scanned by the sensor is varied to compensate for fluctuations in the film speed.

Abstract: A digital transmission system for transmitting, e.g., television sound has two packet type indicators indicating, e.g., mono/stereo transmission. Normally the same packet type indicator is transmitted for a long sequence of packets. To provide synchronizing information to enable, e.g., appropriate timing of a sound signal to the associated video signal, the packet type indicator for a single packet is changed to an indicator which is inappropriate to the packet concerned but is appropriate to another type of packet.

Abstract: In a color television system the luminance signal is split into high and low frequency components, and the high-frequency luminance components are frequency shifted to above the conventional television bandwidth. A conventional receiver uses the low-frequency luminance components (Y.sub.1) and the chrominance component (C), with no cross effects between them. A high-quality receiver can be constructed to recombine the low-frequency and high-frequency luminance components (Y.sub.1 and Y.sub.2 ') giving improved luminance detail, again without cross effects with the chrominance signal. The sound signal (S) is carried between the chrominance and high-frequency luminance. A transmitter (FIG. 4) and receiver (FIG. 5) are described. The system has particular applicability to satellite and cable television.

Abstract: A digital data processor comprises a high speed processor (50) having input ports (52) and output ports (54), a memory (56), and a slow speed support processor (58), the memory being accessible to both the high speed and slow speed processors. The high speed processor can effect processing in dependence upon parameters written into the memory by the slow speed processor and which may have been derived by analyzing data supplied to the slow speed processor from the high speed processor via the memory.

Abstract: A single field or picture of a PAL color television signal is stored in a store and provides a signal at an input (52). The stored signal consists of 2f.sub.sc samples taken at 45.degree. to the U-axis. The signal is separated by a filter (56) and subtractor (58) into a high frequency or chrominance signal and a low frequency or luminance signal. The chrominance signal is delayed by delay means (62) such that the chrominance components of two lines which are an odd number of lines apart are made available simultaneously. These signals are combined by switches (S1, S2) and/or combining circuits (68) to provide a signal at 4f.sub.sc which is combined with the luminance signal in a combining circuit (70) to provide a 4f.sub.sc PAL output (72). The manner of the combination of the chrominance components is changed on an 8-field cycle.

Abstract: A movement detector for television signals measures the difference between maximum and minimum values of the movement components of a picture difference signal over a chosen interval. A television signal at an input (12) is delayed in a picture delay (2), and the delayed and undelayed signals subtracted in a subtractor (1) to form a picture difference signal. This is rectified in rectifier (3) and smoothed in a filter (4). A maximum detector (6) and a minimum detector (7) are coupled to the filter output and are re-set at prescribed intervals. A subtractor (8) determines the difference between the output of detectors (6) and (7) and this is compared with a reference value in a comparator (9), the output of which is sampled and stored in a store (10).