Study of estimating method for actual size of underwater moving objects

A novel method to estimate actual size of underwater moving objects on condition of no any references was proposed. Defocusing effect resulted from different distance between moving objects and lens was analyzed. Blurred edge width in out-of-focus image was detected by using wavelet transformation. The relations between blurred edge width and real distance between objects and lens were deduced based on optical principles. The actual size of the moving object was derived from Gauss formula and lateral magnification expression. The results show that the method gives the actual size of objects and avoids visual error. The method had been applied in the certain international tournament and its effect was excellent.