Fast frequency-guided sequential demodulation of a single fringe pattern

Fast frequency-guided sequential demodulation (FFSD) for demodulating a single closed-fringe pattern is proposed as an improvement of frequency-guided sequential demodulation (FSD). Instead of using optimization to estimate the local frequencies for determining the sign of the phase, the FFSD estimates the local frequencies by directly calculating the gradient of the obtained phase with an undetermined sign. This improvement considerably reduces the computational complexity of the FSD and leads to a faster and simpler method. Simulated and experimental fringe patterns are used to test the proposed method and show that the demodulation speed of FFSD is about 150 times faster than that of the FSD, while the robustness and accuracy remain almost the same.