Abstract: An image processing apparatus for generating visible output images, including visually distinct images. A processor generates displayable image data by writing data to a frame store which is repeatedly read therefrom. Input means, preferably in the form of a mouse, supplies operator defined input signals to the processing means for defining boundary lines (B1, B2) of an object and a sectional line (51), which identifies two boundary lines as defining the object. In addition, storage means are provided for storing data generated in response to the input signals and for storing attribute data defining visual attributes of the objects.