A phase retrieval method for fringe projection profilometry based on the phase pyramid

High-precision phase retrieval is the key step of the fringe projection profilometry, while the traditional multi-frequency phase-shifting method is easy to suffer from noise, which leads to a decrease in measurement accuracy. Based on the local similarity of phases, a new phase retrieval method is proposed in order to improve the accuracy of the phase-shifting and reduce the phase order error. The input images are down-sampled to obtain an image pyramid, and the phase of the high-resolution images is recovered from the low-resolution fringe patterns. Simulation and experimental results show that the proposed method can effectively reduce the phase error in the multi-frequency phase-shifting method and has good robustness and high accuracy.