The oriented spatial filter masks for electronic speckle pattern interferometry phase patterns.

we propose the oriented spatial filter masks for filtering in electronic speckle pattern interferometry (ESPI) phase fringe patterns. We establish the oriented derivative operator that only highlights noise without edges of an image. The noise in the image can be removed while still preserving the edges simply by subtracting the oriented derivative image from original image, which can be implemented with one pass of the oriented spatial filter mask. Further, we make an improvement on the oriented spatial filter mask for enhancing the smoothness. The performance of the oriented spatial filter masks is demonstrated via application to a simulated speckle phase fringe pattern and an experimentally obtained phase fringe pattern and comparison with other directional filtering methods.