电子散斑干涉技术(ESPI)中，基于偏微分方程(PDE)的滤波模型是一种重要的滤波方法。偏微分方程滤波模型中的微分算符通常利用差分近似表示。给出了中心差分、九点差分、高阶差分三种不同的差分格式。以典型有效的方向二阶偏微分方程滤波模型为例，分别利用三种不同的差分格式近似滤波模型中的微分算符，通过模拟条纹图、相位图以及实验条纹图进行了分析研究，结果表明，对于密度变化特别大的条纹图，采用高阶差分格式能够更好地平衡高密度区域和稀疏密度区域的滤波效果，九点差分和中心差分格式需要使用均值滤波做进一步的处理，中心差分格式处理速度最快，高阶差分格式次之，九点差分格式则最慢。

The partial differential equations (PDE) filtering model is an important filtering method in electronic speckle pattern interferometry (ESPI) technology. The differential operator is often approximated by difference scheme in PDE models. Three kinds of difference scheme such as central difference, nine point difference and higher difference are introduced. The representative orientation second order PDE filtering model is selected and analyzed, approximating differential operator in PDE model with three different difference schemes using simulated fringe image, simulated phase image and experiment fringe image. The result indicates the high density region and sparse density region can be balanced preferably with higher difference for large density change image. Nine point difference and central difference schemes should be deposed with average filtering. The processing rate with central difference scheme is the fastest, the higher difference takes the second place, and the nine point difference is the slowest.