a plurality of bandpass filters extract high frequency components of a digital image signal sampled every predetermined unit , thus generating a plurality of high frequency signals . the high frequency signals are added to produce a resultant high frequency signal . on the basis of the value of the resultant high frequency signal , the maximum value or minimum value detected from the high frequency signals is selected . the resultant high frequency signal and the selected maximum or minimum value are added according to determined weights , so that an enhancement signal is generated . edge enhancement is performed using the enhancement signal .