Extracting 3-D structure and focused images using an optical microscope

Describes a novel method for recovering three-dimensional shapes and focused images of microscopic objects. A small sequence of object images is obtained by translating the object through the focused plane of the microscope. The sum-modified-Laplacian (SML) operator is developed to compute local measures of the quality of image focus. The SML operator is applied to the image sequence, and the focus measures obtained at each image point are used to compute local depth estimates. Two algorithms for depth estimation are presented. The first algorithm simply looks for the focus level that maximizes the focus measure at each image point. The second algorithm uses a model to interpolate the focus measures to obtain more accurate depth estimates. The algorithms were implemented and tested on a variety of biological specimens. The authors present a brief description of a fully automated shape-from-focus system that is currently being used to inspect both medical and industrial samples