An Edge-Preserving Nonlinear Error Suppression Method for Fringe Projection Profilometry Based on Low-Pass Guided Filtering

In fringe projection profilometry, phase accuracy is a key factor in determining the ultimate measurement precision. However, errors stemming from the nonlinear response of the projector and camera are introduced into the phase map, manifesting as periodic artifacts that seriously compromise measurement fidelity. Although traditional phase filtering can effectively mitigate these artifacts, it often introduces edge blurring and detail loss. To address this, we first establish models for both the nonlinear error and its propagation and then propose a novel phase filtering algorithm based on low-pass guided filtering. This method effectively suppresses nonlinear artifacts while preserving edges, thereby improving calibration and measurement accuracy without requiring additional hardware. Our algorithm enhances the traditional four-step phase-shifting method: in simulations, it reduces calibration error by 52.2% (from 0.1490 mm to 0.0712 mm), and measurement error by over 36.8% (from 0.0855 mm to 0.0559 mm); in real experiments, these reductions are 54.1% (from 0.1180 mm to 0.0875 mm) and more than 36.7% (from 0.0954 mm to 0.0604 mm), respectively. Experimental results show that our method achieves accuracy comparable to the eight-step phase-shifting method while preserving the efficiency of the four-step method, highlighting its significant practical value.