The Oriented Partial Differential Equation Based on the Discontinuities Measure for Electronic Speckle Pattern Interferometry

The Electronic Speckle Pattern Interferometry (ESPI) is widely used for deformation measurement and nondestructive testing of the optical rough surface in recent years. Removal of the speckle noise is of fundamental importance for accurate extraction of the phase information. The Partial Differential Equation (PDE) filters are well-known for their good processing results, especially the oriented partial differential equation can control the direction of the filtering, which is more suitable for the ESPI image. Furthermore, the filtering degree of different pixels is considered. A new oriented PDE filter model is proposed for the ESPI fringe, in which the DisContinuities Measure (DCM) of an image is introduced to control the diffusion speed. The effectiveness of the proposed method is tested by means of the computer simulation and the experimentation on a real ESPI fringe patterns respectively. The results show that noise is effectively suppressed and the fringe edge is well preserved, even for very dense fringes.