Determining Distance from Defocused Images of Simple Objects

New methods for determining the distance of a simple class of objects from a camera system are presented. The methods use the defocus or blur information in the images formed by an optical system such as a convex lens. Paraxial geometric optics forms the theoretical basis of these methods. The class of objects includes bright points, lines, step edges, blobs, stripes, and smooth edges. Only one defocused image is used. The methods are general in the sense that no restrictions are imposed on the form of the point spread function of the camera system. Computational methods are presented for determining the distance of objects, focal length of the camera system, and the size of the camera’s aperture. Methods are also presented for finding the point spread function, line spread function, and the edge spread function of the camera system. The methods for determining distance have been implemented and verified experimentally. The experimental results suggest that useful depth information can be obtained from defocus information. Both experimental and theoretical error analyses are presented.