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

Describes an approach to reconstructing a shape from it's shaded image in the case where a point light source is at the projection center. This condition well approximates the imaging system of an endoscope. In this case, the image gray level depends on not only the gradient of the object surface but also the distance from the light source to each point on the surface. To deal with this difficulty, the authors introduce the evolution equation for equal-range contours on the surface. Propagating this contour by solving the equation, one can reconstruct a shape. Experimental results far real medical endoscope images of a human stomach inner wall show feasibility of this method, and present a promising technique for morphological analysis of tumors on human inner organs.