A device for monitoring the cutting edge sharpness of a knife is provided with a light source for illuminating the knife and a camera for recording images of the knife. The light source projects at least one reference line onto the knife. In the field of vision of the camera, the reference line crosses the cutting edge of the knife. The cutting edge sharpness of the knife is estimated by the shape of the reference line in an image that captures the knife and its cutting and is recorded by the camera.
