Estimating gray intensities for saturated speckle to improve the measurement accuracy of digital image correlation

Accuracy of digital image correlation (DIC) is deeply affected by illumination variation, especially the local pixel saturation exists. A simple and efficient gray intensity adjustment strategy based on feature matching and standard DIC method is presented for estimating the intensities of saturated pixels. Principle of the strategy based on surrounding pixels around the saturated pixel and the principle of the new proposed strategy are first detailed. Simulations and experiments are performed to verify the efficiency of the proposed strategy. The results indicate that the DIC measurements based on the proposed strategy are able to provide more reliable and accurate results as compared to the existing strategy, even though the large local speckles are saturated.