This paper presents the regional projection contour transformation (RPCT) which transforms a compound pattern or multicontour pattern into a unique outer contour. Two RPCT’s, (1) diagonal-diagonal regional projection contour transformation and (2) horizontal-vertical regional projection contour transformation, are presented. They are applicable to a wide range of areas such as image analysis, pattern recognition, etc. A very large scale integration (VLSI) architecture to implement the RPCT has also been designed based on a canonical methodology which maps homogeneous dependence graphs into processor arrays. In this paper, a linear array has been designed, where an N/2-element vector is used to process a pattern with a size of N x N. It can speed up the recognition process considerably with a time complexity of O (N) compared with O (N2) when a uniprocessor is used. © 1994 IEEE