An image signal processing unit is disclosed which comprises: a contour extraction processing circuit for extracting a contour part from an input image signal, a color signal conversion processing circuit for replacing color signals of the contour part with contour emphasizing color signals on the basis of an output signal from said contour extraction processing circuit, and an image conversion processing circuit for producing a contour emphasized image signal from the input image signal and an output signal from said color signal conversion processing circuit. The image signals input to the image signal processing unit are converted to image signals suitable for display or printing.