An image processor performs emphasis processings suitable for materials to be copied to produce clear copy outputs. The image processor has a digitizing circuit which outputs a digital signal produced by digitizing an image. The processor further has a first detecting circuit which detects an area of the digital signal including a periodic component, a second detecting circuit which detects a character area of the digital signal, and a smoothing circuit which smoothes the digital signal to output a smoothed signal. Either the digital signal or the smoothed signal is selected and outputted by a changeover circuit according to an output of the first detecting circuit. The output of the changeover circuit is differentiated into a plurality of differentiated signals by a differentiating circuit by use of a plurality of different coefficients. One of the differentiated signals is selected and outputted according to the outputs of the first and second detecting circuits.