The details of phase information are lost in the use of mean filtering algorithm to repair singular point by using Stoilov phase shift algorithm, which leads to incorrect phase calculation. In order to solve this problem, a new weighted mean filtering algorithm based on short distance priority was proposed. First, singular points were marked by statistical approach. Then, the size of filter window, which was built basing on the short distance priority principle for each singular point, was up to the number of non-singular points and the shortest distance in current situation. Last, this algorithm used the weighted mean of the non-singular points in the window instead of the singular point to implement singular point correction. The experimental results show that window is more detailed in this method, and the proposed method can effectively remove impulse noise, especially may have advantage in protecting details of phase, and may reduce Root Mean Squared Error (RMSE) less than 0.06 cm in the actual measurement experiments.

Aiming at the problem of mismatching of the extreme points in extremum method for digital speckle images, a new algorithm named the whole pixel extremum displacement measurement for laser speckle images with multi-level crossing was proposed. The extremum method was used to figure out the extreme points of speckle images before and after displacement, constructed extremum value matrix and generated 3-D figure. Then the truncation points were got by multiple specified gray planes crossing 3-D figure. And relative displacement matrix of truncation points was analyzed to calculate displacement of object. The simulation results under the condition of no noise and noise prove that the improved algorithm under guaranteeing the accuracy of displacement measurement, decreases the number of extreme points of error matching and improves operation efficiency 10³ times. The algorithm was applied to the laser mouse positioning and the experimental results show that the displacement of the mobile resolution reached 1 microns, and moving direction angle error was less than 2.72°. It is conclued proves that multi-level truncation extremum displacement method based on laser speckle image is a rapid, efficient and practical algorithm.