Investigation of sub-pixel displacements registration algorithms in digital image correlation

The sub-pixel registration algorithm is considered as a key technique to improve displacement measurement accuracy in a digital image correlation. Various types of sub-pixel registration algorithms have been developed. However, few quantitative researches have been reported to evaluate their performances. This paper investigates three types of most commonly used sub-pixel displacement registration algorithms in terms of registration accuracy and computational efficiency using computer-simulated speckle images and real experimental images. A detailed examination of the performances of each algorithm reveals that the Newton-Rapshon method is most accurate and stable. Accordingly, it is highly recommended to use this method in real applications.