A rapid and accurate gamma compensation method based on double response curve fitting for high-quality fringe pattern generation

Abstract

The gamma effect of structured light illumination devices and camera will yield undesired nonlinear phase errors both in fringe projection system and fringe reflection system. The existing nonlinear correction methods can be classified into two categories: actively modifying the fringe patterns before their projection, or passively compensating the phase error after the fringe patterns are captured. The former needs to capture lots of fringe patterns in advance, while the latter occupies measurement time. In this paper, a rapid and robust active gamma compensation method based on double response curve fitting is proposed for the first time. In the proposed method, the appropriate pre-coding gamma value is determined jointly by the two constructed response curves, so the correction results will not get worse when the number of projected grayscale images decreases and no more than 4 frames of grayscale images are required. Experimental results verified that this method is fast, accurate and easy to implement. With the proposed technique, high-accuracy measurement can be achieved with the conventional 3-step phase-shifting algorithm.