A spatial algorithm to reduce phase wraps from two dimensional signals in fringe projection profilometry

• A new spatial algorithm for phase wrap reduction in 2D phase images is proposed.
• The method is functionally similar to frequency shifting in Fourier space.
• The proposal maintains the robustness at a significantly lower computational cost.
• The positive impact on the subsequent unwrapping procedure is also evaluated.

In this paper, we present a novel algorithm to reduce the number of phase wraps in two dimensional signals in fringe projection profilometry. The technique operates in the spatial domain, and achieves a significant computational saving with regard to existing methods based on frequency shifting. The method works by estimating the modes of the first differences distribution in each axial direction. These are used to generate a tilted plane, which is subtracted from the entire phase map. Finally, the result is re-wrapped to obtain a phase map with fewer wraps. The method may be able to completely eliminate the phase wraps in many cases, or can achieve a significant phase wrap reduction that helps the subsequent unwrapping of the signal. The algorithm has been exhaustively tested across a large number of real and simulated signals, showing similar results compared to approaches operating in the frequency domain, but at significantly lower running times.