FILTER DEVICE FOR ADAPTIVE SUB SAMPLING

摘要

PURPOSE:To obtain high picture quality with high resolution and less hardware by selection and outputting an output of a vertical LPF for a picture having much horizontal change and an output of a horizontal LPF for a picture having much vertical change. CONSTITUTION:The transfer function of the horizontal LPF is expressed as H(Z)=(1+Z<-1>)2.Z<-1>/4 and the transfer function of the vertical LPF is expressed as H(Z)=(1+Z<-1>)2.Z<-1>/4. An output signal of a 1D delay device 5 is subtracted from an output signal of a 1H delay device 2 by a subtractor 17 and the absolute value of the output signal is obtained as a signal 1d from an absolute value circuit 18. On the other hand, an output signal of a 1D delay device 9 is subtracted from an output signal of a 1D delay device 10 by a subtractor 14 and the absolute value of the output signal is obtained as a signal 1e by an absolute value circuit 19, the signal 1d is compared with the signal 1e, and when the signal 1d is smaller than the signal 1e, an output signal 1b is obtained and when larger or equal, an output signal 1c is switched to obtain an output signal 1g. The signal 1g is subject to sub sampling by using a clock whose phase is inverted at each line by a sub-sample switch 21 and a signal 1h is obtained as the output signal.