On the basis of analysis of the problem of the traditional threshold function

the hard threshold function and the soft threshold function

a new threshold function is proposed.Compared with the traditional thresholding functions

it is more simple in expression

as continuous as the soft-thresholding function

and has a higher order derivative which makes some kinds of mathematical disposals convenient.With this threshold function

through changing the value of the parameters

the constant deviation between threshold wavelet coefficient and original wavelet coefficient can be adjusted and the curve in transit area smooth is made

which overcomes the disadvantages of non-continuity in hardware threshold method and the deviation in soft threshold method.The experimental results show that the proposed method presents better MSE perfofinance and has both better subjective visual effect and the PSNR than the traditional approaches.