Performance of sub-pixel registration algorithms in digital image correlation

Developments in digital image correlation in the last two decades have made it a popular and effective tool for full-field displacement and strain measurements in experimental mechanics. In digital image correlation, the use of the sub-pixel registration algorithm is regarded as the key technique to improve accuracy. Different types of sub-pixel registration algorithms have been developed. However, little quantitative research has been carried out to compare their performances. This paper investigates three types of the most commonly used sub-pixel displacement registration algorithms in terms of the registration accuracy and the computational efficiency using computer-simulated speckle images. A detailed examination of the performances of each algorithm reveals that the iterative spatial domain cross-correlation algorithm (Newton-Raphson method) is more accurate, but much slower than other algorithms, and is recommended for use in these applications.