British Broadcasting Corporation

Alan Roberts

Richard Storey

A video display system such as a broadcast receiver or a studio monitor is designed to display both MAC-type input signals and HDTV-type input signals, only the latter being of constant luminance type. For MAC signals a normal Y, U, V to R, G, B, decoder matrix is used comprising amplifiers (18, 20, 22) resistors (24A, 24B, 26A, 26B, 28A, 28B, ) and further amplifiers (24, 26, 28). The output is applied to a CRT display device (30) having a conventional gamma factor. For HDTV signals, the decoder matrix is augmented by a correction matrix having six or eight circuit sections. Each circuit section comprises resistors (42, 44, 46), an operational amplifier (40), and circuitry including diodes (48, 50) for selecting the output only over a portion of the permissible color range.

Video display system using an improved color signal technique

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).

Movement detector for television signals

Dot matrix characters are rounded by interpolating quarter dots in the angles of diagonal strokes with the feature that the video signal is a line interlaced signal; the diagonals are detected as predetermined logical combinations of an undelayed signal, a dot-delayed signal, a line delayed signal and a line-plus-dot delayed signal; the quarter dots are interpolated in real time as the diagonals are detected but are interpolated in a first one of the said signals in first fields and in a second one of the said signals in the second, interlaced fields, the second signal being line-delayed relative to the first signal.

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Coulsdon, United Kingdom

Alan Roberts