[6] Jie He, Rongzhen Zhou, Zhiliang Hong. Modified fast climbing search auto-focus algorithm with adaptive step size searching technique for digital camera[J]. IEEE Transactions on Consumer Electronics, 2003, 49(2): 257～262

[9] D. L. Donoho. De-noising by soft-thresholding[J]. IEEE Transactions on Information Theory, 1995, 41(3): 613～627

[10] D. L. Donoho, I. M. Johnstone. Adapting to unknown smoothness via wavelet shrinkage[J]. J. American Statistical Association, 1995, 90(432): 1200～1224