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A Simple Reversible Watermarking Scheme Based on Difference Expansion
Chao-Ming Wu,Cheng-Kang Wu,Houshou Chen 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
A simple reversible watermarking scheme based on block-wise difference expansion is proposed. Pixels in a block are expanded with respect to a common reference point. The maximum capacity will exceed 0.5 bpp if the block size is larger than 2. According to local variances of the reference points, blocks introducing small distortion by difference expanding are selected firstly to embed watermark. In Tian’s difference expansion algorithm, the embedding of the location map causes large overhead cost, apparently in low payload region. A good lossless compression algorithm is required to reduce this cost but the complexity is increased. In the proposed algorithm, a simple all 0 pattern is used to distinguish between non-expandable and expandable blocks. In this way, the location map is no longer necessary and the complexity of the scheme will be reduced.