https://www.springerprofessional.de/en/reconstruction-of-3-dimensional-scenes-using-depth-from-defocus-/14227406 Abstract This paper demonstrates how multi-layered neural networks can be used to obtain the relative depth variation of textured scenes. The system employed makes use of two differently focused images taken by a tele-centric imaging setup. The relative variation of blur of corresponding regions in the two images was used to calculate the relative depth. The neural network is used to predict the degree to which a particular region is blurred. To make the neural network predict blur irrespective of the texture of the scene, it was trained on highly textured fractal images.