Abstract: Analysis of images or specimens which exhibit visually distinguishable component areas of a plurality of different types, to determine the relative abundances, average sizes or other characteristics of such areas, is facilitated by a semi-automatic scanning system which includes an on-line data processor. The apparatus combines the superior area recognition ability of the human operator with the speed and ease of operation of fully automatic systems. A keyboard control unit has a plurality of manually operable keys any one of which may be actuated to drive the stage motor of a microscope through which the operator views the specimen and each of which generates a distinctive signal identifying a different specific type of area in the specimen. The data processor receives stage translation signals and the area classification signals and computes the desired data which may be visually displayed following a period of scanning.