数字投影和成像系统的Gamma非线性效应是导致相位测量轮廓术（PMP）测量误差的重要原因。目前大多采用多帧条纹图进行Gamma校正，使测量的实时性受到限制。提出了一种Gamma校正方法，利用正交光栅像的傅里叶频谱分布计算Gamma值，再根据此Gamma值对投影相移条纹进行Gamma逆变换，实现投影条纹输入值的提前校正，以获取具有良好正弦性的结构条纹，从而降低PMP相位测量误差。校正过程中只需一帧条纹图，而且考虑了测量系统的离焦效应。实验证实了该方法的有效性和正确性。

Gamma nonlinearity of a digital camera-projector pair leads to obvious phase measurement errors in phase measuring profilometry (PMP). Among the conventional gamma correction methods, most of them use plenty of fringe patterns to implement gamma correction, which is unsuitable for real-time measurement. Based on the Fourier spectrum analysis of an orthogonal sinusoid grating, a correction method for the evaluation of the gamma value is proposed. The evaluated gamma value is then pre-encoded into computer-generated phase-shifting fringe patterns to obtain well-sinusoidal fringe patterns, the errors of the PMP are reduced. Only one pattern is needed and the defocusing effect of the measuring system is considered in the correction. Experiments have verified the feasibility and validity of the proposed method.