Abstract

A method and apparatus are disclosed for determining whether a shape or pattern exists anywhere in a particular image represented by a matrix of digital data signals. In the preferred embodiment, a suitably programmed general purpose computer provides means for storing the matrix of data signals representing the first image, computing the complement of the first image matrix and storing the complement image matrix, creating a structuring element representative of the target shape to be recognized and storing a matrix of digital data signals representing that structuring element, and creating a second structuring element equal to the window complement of the first structuring element and storing the second structuring element. One or more substantially identical neighborhood transformation stages are then employed for electronically eroding the first image with the first structuring element to form a first transformation matrix, and electronically eroding the complement image matrix with the second structuring element to form a second transformation matrix. The corresponding points of the first and second transformation matrices are then combined to form a result matrix wherein each non-zero point represents the location of the desired shape or pattern in the first image.