On the Determination of Threshold in Threshold based De noising by Wavelet Transform

The hard threshold t=cσ is proved to be efficient in threshold based nonlinear filtering by wavelet transform.Generally speaking,the optimal c varies with the signals and the intension of the added noise.Here we construct a function that approximates an equivalent function of the MSE of the recovered signal.The approximate optimal c can be determined by minimizing the function.Simulations show that the function we construct is consistent with the MSE of the filtered signal and the so selected c is reasonable.