Theoretical analysis of color decoupling method in multi-frequency color fringe-projected shape measurements

Multi-frequency color fringe projection is one of useful techniques proposed in recent years to measure 3D shape of objects in a single shot. In this technique, color decoupling is an indispensable step of analyzing the captured fringe pattern. This paper presents an algorithm to implement a fast and clean color decoupling. First, the cross talk among color channels of commercial CCD and projector is modeled as color coupling equation. Then empirical mode decomposition are used to solve the equation. Consequently, the extraction of the low, medium and high fundamental frequency components from the color pattern is accomplished, facilitating the subsequent phase calculation and shape recovery.