Study on Choice of Method of Filter in De-noising and Effect of Nonlinear
去噪和非线性效应中滤波方法的选择研究

For the characteristics in de-noising and the effect of nonlinear, basic theorems in de-noising and the effect of nonlinear are analyzed, Three methods (the filter of rectangle window, hanning window and threshold restriction) of their advantages and disadvantages are given. The effect of measuring precision for fourier transform profilometry (FTP) among three different methods of filter are compared. Computer simulations indicate that threshold restriction is the best method for de-noising in linear, but the methods of rectangle window and hanning window are better than that of threshold restriction in nonlinear. The effect of nonlinear is for the most part in experiments, the result shows that the methods of rectangle window is the best while that of threshold restriction is the worst to regain the shape of object. Compared the rectangle window with the hanning window in filter of Computer simulations and experiments, the effect of rectangle window is better than the latter.