Reversible Fragile Watermarking for Multichannel Images with High Redundancy Channels

Abstract

The paper presents a methodology to protect the integrity of multichannel images, having some highly redundant channels, by means of a reversible fragile watermarking algorithm. The watermark embedding phase uses a lossless compression method to compress the high redundancy channels, stores the compressed stream into their most significant bits, then embeds a secret fragile watermark by modifying the least significant bits of the high redundancy channels. In case the watermarked image is not modified, the host image can be perfectly reconstructed; otherwise, the modified area can be detected and located with very high probability and the area that has not been forged can be restored as in the original host image. The embedding of the watermark is performed by a Genetic Algorithm in the Karhunen-Loève Transform (KLT) domain: the use of a secret space defined by the KLT guarantees both security of the method and a high sensitivity in the detection of the forged areas.