Patent ID: 7318079

Claim:
A method for filtering video input signal having a sequence of signal values, to provide a high-pass filtered video output signal having a sequence of filtered signal values for video display, the method comprising the following steps: a) selecting a first signal value of the video input signal to be filtered and at least one second signal value preceding the first signal value in the video input signal sequence and at least one third signal value following the first signal value in the video input signal sequence; b) determining an interval defined by the at least one second signal value and the at least one third signal value, with a first interval boundary defined by the at least one second signal value and a second interval boundary defined by the at least one third signal value; c) determining a mean value of the interval from the at least one selected second signal value and the at least one selected third signal value; d) determining whether the first signal value lies within the interval; e) if the first signal value lies outside the interval, determining a first distance between the first signal value and the first interval boundary and a second distance between the first signal value and the second interval boundary and a third distance between the first signal value and the mean value to provide a first, a second, and a third distance value, and selecting a signal value from a value range between the smaller of the first and second distance values and the third distance value to provide the selected signal value; f) if the first signal value lies within the interval, selecting a signal value from a value range between zero and half the interval width to provide the selected signal value; and g) setting the sign of the selected signal value depending on the position of the first signal value relative to the mean value to provide a value for the high-pass filtered video output signal.