U.S. Philips Corporation

Christopher M Carey Smith

Franciscus W Vreeswijk

Use is made of a digitally assisted DATV to effect a bandwidth reduction encoding and bandwidth reduction decoding, in addition to MAC-coding and MAC-decoding, of at least three picture signal channels (PC) each having a different picture signal refresh period equal to, for example, 80, 40 and 20 ms which are coupled via a time-division multiplex circuit (MUX). For with the diversity of picture signal sources, it was found that distinguishing during the picture signal processing between a film mode (SW1, T40) and a non-film mode (SW1, T20) results in a significantly improved high-definition picture resolution. This distinction is expressed at the DATV by one information bit (FM'). During the non-film mode (SW1, T20) three Y-liminance channels (PC11, PC13 and PC12) of 80, 40 and 20 ms and two U and V-chrominance channels (PC21 and PC22) of 80 and 20 ms are operative. During the film mode (SW11, T40) the Y-channels (PC11 and PC13) and the U and V-channels (PC21 and PC23) of 80 and 40 ms are only operative.

High-definition television systems

A television picture memory (MEM) containing digital picture signal values associated with picture elements (PIX) is coupled via a picture signal value comparison circuit (COM1) and an absolute value circuit (ABS1) to an adaptive threshold circuit (THR) for the picture signal differences. In order to obtain a motion detection with a directional sensitivity in the horizontal and vertical direction, the threshold circuit (THR) has an adaptive horizontal and vertical threshold value - adapting circuit (ADA) which produces the adaptive threshold values (HI and VI) via maximum value passing circuits (H MAX and V MAX) which are coupled to the memory (MEM) via an absolute value circuit (ABS2), a picture signal comparison circuit (COM2) and a signal combining circuit (AVE2), and by-passing it. The comparison circuit (COM2) is operative for the horizontal threshold value (HI) with picture elements in the line direction which are more or less adjacent to an instantaneous picture element and picture element values which are derived via the signal combining circuit (AVE2) from the picture elements of one of the more or less adjacent, superjacent or underlying lines belonging to the instantaneous, preceding or subsequent field period. The comparison circuit (COM2) is operative for the vertical threshold value (VI) with picture elements in the field direction that are more or less adjacent to the instantaneous picture element and picture element values which are derived via the combining circuit (AVE2) from the picture elements of one of the more of less adjacent, superjacent or underlying lines belonging to the instantaneous, preceding or subsequent field period.

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Eindhoven, Netherlands

Christopher M Carey Smith