A Class Of Edge Preserved Oriented Partial Differential Equations Filter Models And Theirs Application

Optical measurement technology with the merit of whole-field, non-contact nondestructive has been widely used in many fields of science and engineering. In most optical measurement technology, the measured physical quantities are wrapped in optical fringe images. Since the optical images got from experiments are with strong noises, the primary task is to carry out optical fringe images filtering in optical measurement technology. It is of great importance and challenge to remove the noise while preserve all fringes edges. Due to the fact that optical fringe images are with obvious direction, filtering along the fringe oriention (referred to oriented filtering) is an effective method to preserve the fringe edges.This dissertation mainly makes a study of edge preserved oriented partial differential equations filter models. It mainly includes:A review of the existing the oriented filtering models is made; Further a series of new oriented partial differential equations filtering models are derived based on the variational method and the existing oriented partial differential equations; A investigation of the performance of the main oriented partial differential equations filtering models is made; Finally, some new oriented partial differential equation filtering models for some different optical measurement fringe images filtering are applied and better filtering results are achieved.The main work in this dissertation is as follows:(1) The existing main oriented filtering models are reviewed in details. Their basic principle and construction of these oriented filtering models are briefly described.(2) On the basis of the existing oriented partial differential equations, further we derive a class of new oriented partial differential equations filtering models based on the variational methods. It mainly includes:a class of new single oriented partial differential equations filtering models, a class of new selective oriented partial differential equations filtering models, a class of new coupled oriented partial differential equations filtering models, a class of combined single oriented partial differential equations filtering models and a class of new double oriented partial differential equations filtering models. (3) We make a comprehensive comparison study of the representative oriented partial differential equations filter models. It mainly includes:the choice of parameters, the influence of the fringe orientation angle θ, the influence of the diffusion speed control function g (-)on the filtering results, the computational time of every models for one time iteration, the maxima of time step△tmax of every models and so on.(4) The application of the some new oriented partial differential equations filtering models is conducted. We use some new oriented partial differential equations models for some different optical fringe images filtering. Since these optical fringe images are with variable density, we apply some new double oriented partial differential equations for filtering.The oriented partial differential equations are proved to be an effective tool for the optical fringe images filtering and preserving for all fringe edges. In this disseration, the research work provides an effective tool for optical fringe images filtering with important application value.