The invention relates to reducing the recognition of a predefined parking position using a 2-D camera image to a one-dimensional system for extracting parking space markings and/or parking space boundaries. For this purpose brightness curves are measured within a camera image by means of predetermined and already known evaluation lines, in order use an optical contrast of a parking space boundary in relation to the adjacent road surface and/or pavement for recognizing the parking space boundary. Different algorithms are proposed, in order to conclude the presence or absence of a predefined parking position from the one-dimensional brightness curves.