LAUSR

This study presents a new strategy of retrieving displacement fields from two different images or two video frames obtained at different times using an iterative optical flow method. First, illumination modeling and image preprocessing are required before the displacement calculations can be performed. Due to the displacement continuity assumption, the displacement differences between the neighboring points are small. Then, the initial displacements of the unprocessed points are determined by the displacements of the processed neighboring points. Next, an iterative optical flow method is performed with a small window size to obtain the displacement offsets between the matching point pairs. The calculation is performed at the subpixel level in each iteration, and thus image interpolation is necessary. In this paper, image upsampling of the deformed image is applied using bi-cubic spline interpolation to achieve the subpixel intensity before all the calculations. This improvement avoids the requirement for image interpolation to be in all iterations. Several numerical tests and real image datasets were used to validate the performance of the proposed method. The results were compared with those obtained by a traditional digital image correlation method using the traditional forward additive Newton–Raphson algorithm and the iterative least square algorithm. Both tests showed that the proposed algorithm exhibits excellent performance regarding computational accuracy and speed.