This paper considers the reconstruction of a shape from a stack of images obtained by optical sectioning. To this end we describe three algorithms relying on the scalar optics model of light propagation of which the most involved is the deconvolution approach. This approach produces a sequence of deblurred images. We improve the deconvolution approach by implementing a novel stopping criterion for the iterative process. The performance of the algorithms is illustrated by numerical experiments on microscopic images of biological cells.