VERFAHREN ZUR UMWANDLUNG EINER VIDEOSIGNALWIEDERGABEFREQUENZ

摘要

The invention relates to a method wherein it is possible, by digital signal processing taking place in the receiver, to reduce errors caused in a television picture by an interlaced transmission standard and a low field frequency. The transmitted interlaced (50 Hz/2:1) signal is converted in the receiver either to a non-interlaced (50 Hz/1:1) signal or to an interlaced (100 Hz/2:1) signal. The higher display frequency transfers the errors to higher frequencies, whereupon they no longer disturb the viewer. The conversion takes place by means of a weighted median filter operating in a 3*3 window. In the window, the first line is from the preceding field in the memory and the two others are from the latest received field. The filter interpolates a new dot according to these data. The structure of the filter selects implicitly temporal interpolation in a stationary picture and spatial interpolation for moving objects. By altering the coefficients of the weighted median filter it is possible to optimize the filter to operate either in a moving picture or in a stationary picture. The method can be carried out using a VLSI circuit. <IMAGE>