Film mode detection procedure and device

摘要

A film mode provides for increased vertical resolution in the case of film-scanned source signals. An information item on whether such a source signal is present can be transmitted together with the television signal. An evaluation in the receiver, however, necessitates a not inconsiderable hardware complexity under certain circumstances. In addition, it is not ensured that all television transmitters or all programmes transmit this additional information. A check is made for all vertically adjacent pairs of pictures whether the amplitude of the two pictures vertically between these from the two adjacent fields is between the amplitudes of the pair of pictures. These comparison results are combined within each field. These results of the combination must correspond to a particular pattern of in each case a particular number of fields for the film mode to be detected. The switching-off criteria are less strict. A certain number of 'wrong' combination results may occur within a predetermined number of fields. Film mode is only switched off when this number is exceeded. <IMAGE>