Adaptive phase retrieval algorithm for local highlight area based on a piecewise sine function.

Phase measuring profilometry (PMP) has been widely used in industries for three-dimensional (3D) shape measurement. However, phase information is often lost due to image saturation results from high-reflection object surfaces, leading to subsequent 3D reconstruction errors. To address the problem, we propose an adaptive phase retrieval algorithm that can accurately fit the sinusoidal fringes damaged by high reflection in the saturated regions to retrieve the lost phase information. Under the proposal, saturated regions are first identified through a minimum error thresholding technique to narrow down regions of interest and so that computation costs are reduced. Then, images with differing exposures are fused to locate peak-valley coordinates of the fitting sinusoidal fringes. And the corresponding values of peak-valley pixels are obtained based on a least squares method. Finally, an adaptive piecewise sine function is constructed to recover the sinusoidal fringe pattern by fitting the pattern intensity distribution. And the existing PMP technology is used to obtain phase information from the retrieved sinusoidal fringes. To apply the developed method, only one (or two) image with different exposure times is needed. Compared with existing methods for measuring reflective objects, the proposed method has the advantages of short operation time, reduced system complexity, and low demand on hardware equipment. The effectiveness of the proposed method is verified through two experiments. The developed methodology provides industry an alternative way to measure high-reflection objects in a wide range of applications.