[1] [1] Li T L, Sundarehan M K. Adaptive image contrast enhancement based on human visual properties [J]. IEEE Trans Medical Imaging,1994,13(4):573-586.

[2] [2] Kim J Y, Kim L S. An advanced contrast enhancement using partially overlapped sub-block histogram equalization[J]. IEEE Trans Circuits and Video Technology,2001,11(4):475-484.

[3] [3] Chang D C, Wu W R. Image contrast enhancement based on a histogram transformation of local standard deviation [J]. IEEE Trans Medical Imaging, 1998,17(4):518-531.

[4] [4] Donoho D L. De-noising by soft-thresholding[J].IEEE Trans Information Theroy,1995,41:613-627.

[5] [5] Laine A F, Schuler S. Mammographic feature enhancement by multiscale analysis[J].IEEE Trans Medical Imaging,1994,13(4):725-740.