Bian Yang Martin Schmucker Xiamu Niu Christoph Busch Sheng-He Sun Integer-DCT-based reversible image watermarking by adaptive coefficient modification. 218-229 2005 conf/sswmc/2005 Security, Steganography, and Watermarking of Multimedia Contents db/conf/sswmc/sswmc2005.html#YangSNBS05