Gamma estimation method based on phase error coefficients vector in digital fringe projection system

For phase-measuring profilometry systems, gamma effect is important to the accuracy while its gamma factor cannot be measured goodly when there are a few images. To tackle the problem, this paper proposes a novel idea: calculate the phase errors coefficients vector (PECV) of a series of heuristic gamma values, and measure the distances from the PECV of the current measurement to those, respectively; then, the gamma corresponding to minimal distance is the measured gamma factor. The idea does not measure the gamma factor straightforwardly and novelly measures the phase error distances. The technique is fast and robust, and only needs at least six images. Experimental results demonstrate the feasibility and performance.