An Effective Reversible Watermarking for 2D CAD Engineering Graphics Based on Improved QIM

Quantization index modulation (QIM) is widely used in watermarking, but QIM cannot be applied to reversible watermarking directly due to its inherent limitations. In this paper, an improvement is made to QIM to make it suitable for reversible watermarking. Based on the improved QIM (IQIM), a reversible watermarking scheme for 2D CAD engineering graphics is proposed. The relative amplitudes and the relative phases of entity vertices are used as hosts to carry the watermark, respectively, and the data recovery is controlled by a secret key. Experimental results indicate that the proposed scheme can strike a good balance between capacity, imperceptibility, robustness, security and complexity.