Televison noise reduction system for a signal source having variable

Abstract

The correction factor applied to a delayed television signal in a television noise reduction system and the complement of that factor applied to the undelayed television signal from which the delayed television signal is derived after averaging with the weighted delayed signal of an earlier of the preceding television frames, are modified in accordance with whether the source of the origninal television signals is or is not repeating at least one field of the television frames before going on to the next. The variation of the correction factor can also be made to depend on the number of repetitions of each frame. In an automatic system, operating in connection with a film scanner capable of scanning a motion picture film at different speeds (frames per second) to produce television signals in accordance with either the American or European television standard, the correction factor is set at the value 1 whenever a film frame is scanned for more than two half-frame television fields. For this purpose, a signal change from one state to another as soon as one full television frame has been provided by scanning a film frame. At the same time that the correction factor is set at the value 1, the writing-in of television signals into the store which produces the delayed television signal is blocked, so that the previously written-in signal, representing the same frame, is used, and the accumulation of correlated noise in the output signal is prevented.