Described is an assistance device for providing imaging support to an operating surgeon during a surgical procedure involving at least one medical instrument. The assistance device comprises a camera, a display unit, a manipulator coupled to the camera, a manipulator controller and an image processing unit. The image processing unit includes an instrument detection module for detecting at least one target structure that represents the instrument being used in the frame in question by identifying a predetermined distinguishing feature, and for extracting position information that indicates the position of the target structure in the frame. The instrument detection module identifies an image segment as the predetermined distinguishing feature, said image segment being characterized by a color saturation that is equal to or less than a predefined color saturation and by a contour line that delimits the image segment and has at least one rectilinear section.