Double-shot inverse-phase color fringe projection profilometry using two-step phase shifting

A double-shot inverse-phase color fringe projection profilometry is proposed to measure 3D shape information by using two-step phase shifting. Each of these two patterns encoded with two sinusoidal patterns and one uniform intensity pattern is projected by a digital projection and recorded by a color CCD camera. Firstly, the captured color fringe patterns are separated into its RGB components and two-step phase shifting is composed with red and blue components. Secondly, the dominant error sources are analyzed to reduce the variable errors and the red and blue components are filtered with a band-pass filter by using fast Fourier transform. Finally, 3D shape information is decoded by applying 1D Hilbert Transform and the phase errors are weakened with the sum of inverse-phase. Simulation and experimental results demonstrate that the proposed approach is able to effectively suppress phase errors.