三步空域准相移技术是一种单帧相位解调技术，适用于动态条纹相位分析。本文在已有的三步空域准相移技术的基础上，提出了一种改进的三步空域准相移技术。改进后，在计算每个像素点相位时，可以根据具体情况，灵活选择邻域范围，调节所使用像素点的个数，有利于噪声的隔离，避免误差的传播，从而提高动态条纹分析中相位解调的精度。

Three-step spatial quasi-phase-shifting technique is able to demodulate the phase from a single frame of fringe pattern. This technique is suitable for dynamic fringe analysis. An improved three-step spatial quasi-phase-shifting technique is presented in this paper. According to actual situation, the number of pixels and the size of neighborhood are able to be tuned arbitrarily to calculate the phase of each pixel. It is conducive to the noise isolation, the error-propagation prevention, and the accuracy improvement in phase demodulation for dynamic fringe analysis.