An input signal is accurately separated into a component in which a change in signal level is sharp and having a large edge, and the other components.A narrow band non-linear filter extracts an edge component in a relatively narrow frequency band from an input signal and outputs the signal. A wide band non-linear filter extracts an edge component in a relatively wide frequency band from the input signal and outputs the signal. A selector outputs a signal composed of the signal where an edge portion is replaced, based on a differentiated value of the signal sent by a differentiator, as the edge component of the input signal. An adder subtracts an output signal from the input signal and outputs the calculated output signal as the edge component of the input signal. This process, may be applied to an image processor.