CONTOUR EMPHASIS CIRCUIT

A contour emphasis circuit receives a video signal from a TV camera for picking up an image formed through a variable magnification factor optical system such as a microscope. The contour emphasis circuit comprises a plurality of contour extractors having different frequency characteristics for generating contour emphasis signals in accordance with the video signal, a selector for selecting one of the plurality of contour extractors in accordance with a magnification factor set to the optical system, and an adder for adding the contour emphasis signal from the contour extractor selected by the selector to the video signal. Optimum contour emphasis is attained in accordance with the magnification factor set to the optical system and the deterioration of an S/N ratio by the contour emphasis is prevented.