Wanpeng Cao Rensheng Che Dong Ye An illumination-independent edge detection and fuzzy enhancement algorithm based on wavelet transform for non-uniform weak illumination images. 192-199 2008 29 Pattern Recognition Letters 3 http://dx.doi.org/10.1016/j.patrec.2007.09.012 db/journals/prl/prl29.html#CaoCY08