Chu-Hsing Lin Chen-Yu Lee Shu-Yuan Lu Shih-Pei Chien Unseen Visible Watermarking for Gray Level Images Based on Gamma Correction. 236-243 2011 FGIT-FGCN (1) https://doi.org/10.1007/978-3-642-27192-2_28 conf/fgit/2011fgcn-1 db/conf/fgit/fgcn2011-1.html#LinLLC11