Shape reconstruction from an endoscope image by shape from shading technique for a point light source at the projection center

This paper presents a method for reconstructing the 3D shape of an object from its endoscope image based on image shading. The primary problem is that the endoscope has a light source near the object surface. Most of the conventional shape from shading methods assumed that the light source was distant from the object surface and simplified the analysis. To deal with the near light source, we use the configuration of the endoscope that the light source of the endoscope is well approximated by an imaginary point source at the projection center. In addition, we introduce a notion of equal distance contours of the object surface; by propagating the contours using the image shading, we reconstruct the object shape. This is an extension of the Kimmel-Bruckstein algorithm of shape from shading to the endoscope images. Experimental results for real medical endoscope images of the stomach wall show the feasibility of this method and also show its promising availability for morphological analyses of tumors on human inner organs. (C) 1997 Academic Press.