Pre-qualifying DIC performance based on image MTF correlation coefficient

Abstract

Attempts on developing the method for qualifying digital image correlation (DIC) method results, especial the displacement field, is presented in this paper. By taking a series images from center and margin of imaging field, DIC method is implemented to calculate displacement fields with respect to center of imaging field as origin of movement. Concurrently, residual displacements are obtained by subtracting mean value from the obtained displacement fields. The residual displacements are considered to be errors and mainly introduced by the imaging system of DIC. In this paper, modulation transfer function (MTF) is adopted to relate the residual displacement, DIC quality, with imaging system performance. By investing the MTFs cross-correlation values of all positions with respect to the reference image, a potential qualitative method for inspecting the DIC results based on sub-image MTF cross-correlation is proposed in this paper.