Abstract: Development in digital image correlation in the last twodecades has made it a popular and effective tool for full-field displacementand strain measurements in engineering in general, and experimentalmechanics in particular. In DIC, the sub-pixel registration algorithm isregarded as a key measure to improve accuracy. This paper introduces thebasic principles and several sub-pixel displacement registration algorithms.It also illustrates the shortcomings and advantage of differentalgorithms on the basis of a survey of recentresearches. With the further improvement of the algorithm accuracy as wellas the development of hardware, the future of this method is promising interms of widespread applications.