Deformation measurements using mutual information: principle and applications

The paper presents a new method applied to measure displacement fields using mutual information concept. Based on analysis of digital image sequences, we propose the formulation derived from the mutual information between subsets in the un-deformed and deformed image. The quantity of the mutual information between two subsets establishes a criterion of their mutual dependence based on the notion of information connection between them. We can obtain the integer pixel displacement for the corresponding subset. And the accurate displacement field is obtained by using sub-pixel technique. In the experiments, the method is validated and the resulting solution can show accuracy to 0.02 pixels. This method was also applied successfully to determine the displacement fields of laminated composites of AS4/PEEK[0/±45/90]_7s under uniaxial compression.