Patent ID: 8018532

Claim:
A video signal processing apparatus for edge enhancement comprising: a signal level detector to detect signal levels of an input video signal at an N number of pixels located adjacent to one another in a specific scanning direction, N being an even number of four or larger; an absolute value producer to obtain a difference between the signal levels and produce an absolute difference that is an absolute value of the difference at each pair of adjacent two pixels among the N number of pixels, thus obtaining an (N−1) number of absolute differences; a nonlinear arithmetic processor to apply nonlinear arithmetic processing to a particular one absolute difference among the (N−1) number of absolute differences to subtract the particular one absolute difference from a predetermined initial value to obtain a subtracted value, and to obtain an absolute value of the subtracted value, the absolute value of the subtracted value being set to a predetermined value if equal to or lower than the predetermined value, the particular one absolute difference being obtained from a pixel pair of two adjacent pixels located in the middle of the N number of pixels aligned in the specific scanning direction; an adder to add the absolute value of the subtracted value subjected to the nonlinear arithmetic processing and an (N−2) number of absolute differences among the (N−1) number of absolute differences, the (N−2) number of absolute differences being not subjected to the nonlinear arithmetic processing, thus obtaining an evaluation function value; a plurality of low-pass filters having different filter characteristics for applying filtering processing to the input video signal, thus outputting video signals having high-frequency components attenuated depending on the different filter characteristics; and a selector to select the input video signal with no filtering processing applied for the edge enhancement if the evaluation function value is larger than a reference value whereas one of the video signals output from the low-pass filters for the edge enhancement if the evaluation function value is equal to or smaller than the reference value, the smaller the evaluation function value, selected being one of the video signals having the high-frequency components attenuated more.