Efficient Implementation of Parallel Image Reconstruction Algorithms for 3D X-Ray Tomography

This paper deals with efficient parallel implementations of reconstruction methods in 3D tomography. Depending on the method, we use two main approaches to parallelize the algorithms and we propose different optimizations in order to improve the efficiency of the parallel algorithms. These improvements are based either on the minimization of the communication time by using optimized collective communication algorithm, or by overlapping the communication by the computation. Experimental results on different distributed parallel machines are presented which highlight the improvements obtained

Optimal covering of a straight line applied to discrete convexity

International audienceThe relation between a straight line and its digitization as a digital straight line is often expressed using a notion of proximity. In this contribution, we consider the covering of the straight line by a set of balls centered on the digital straight line pixels. We prove that the optimal radius of the balls is strictly less than one, and can be expressed as a function of the slope of the straight line. This property is used to define discrete convexity in concordance with previous works on convexity

New notions for discrete topology

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