Image Cross-Correlation for Calculating the Position Coordinates of Round Objects and Measuring Their Dimensions

We propose a technique for determining the coordinates of the position of a round object in an image and its diameter. The method is based on calculating the cross correlation value of a fragment of the analyzed image with several characteristic pattern images in order to simultaneously determine which pattern and with what offset relative to the considered fragment are the most suitable. The technique allows not only to calculate the size and coordinates, but also to determine whether the object is absent in the field of view. Its feasibility and practical applicability are shown using the example of an algorithm for analyzing the ball-type wire bonding on the die surface, used in the assembly of integrated circuits. The algorithm can be used for nondestructive testing in the production of semiconductor products before the packaging. The algorithm allows not only to measure the diameter of the ball and determine whether its coordinate is within tolerance or not, but also to establish whether there is a connection at all.