Parallelization of perceptual grouping on distributed memory machines

We propose architecture independent parallel algorithms for solving perceptual grouping tasks on distributed memory machines. Given an n/spl times/n image, using P processors, we show that these tasks can be performed in O(n/sup 2//P) computation time and 20/spl radic/(P)T/sub d/+8(logP)T/sub d/+(40n//spl radic/(P)+20P)/spl tau//sub d/ communication time, where T/sub d/ is the communication startup time and /spl tau//sub d/ is the transmission rate. Our implementations show that, given 7K line segments extracted from a 1K/spl times/1K image, the line grouping task can be performed in 1.115 seconds using a partition of CM-5 having 256 processing nodes and in 0.382 seconds using a 16 node Cray T3D. Our code is written in C and MPI message passing standard and can be easily ported to other high performance computing platforms.