Introduction

As used in this article, the term "digital image correlation" refers to the class of non-contacting methods that acquire images of an object, store images in digital form and perform image analysis to extract full-field shape, deformation and/or motion measurements. Digital image registration (i.e. matching) has been performed with many types of object-based patterns, including lines, grids, dots and random arrays. One of the most commonly used approaches employs random patterns and compares sub-regions throughout the image to obtain a full-field of measurements. The patterns may occur on solid surfaces or may be a collection of particles in a fluid medium.