Robust Reversible Watermarking Based on Normalized Correlation Combined with Cdma Techniques

In this paper, the Normalized Correlation based Quantization Index Modulation (NCQIM), Least Significant Bit (LSB) and Code Division Multiple Access (CDMA) techniques are combined for reversible watermarking. By using this method, the normalized correlation is calculated between the host signal and a random signal. Then the modulation is performed on generated normalized correlation by using codeword from the codebook associated with the embedded information. The codebooks are designed by using uniform quantizer for modulation. Then the LSB method is used. In this method, the LSB values of each pixel in the image are modified. Then CDMA technique is applied. Then watermark embedding is done through the above performed modulation. This watermark signal is used to produce minimum distortion in valumetric scaling and additive noise attacks. At decoder side, the watermark is extracted using the technique which is done at embedder side. The proposed method is simulated on different images and the watermark imperceptibility is achieved by using the parameter Peak Signal to Noise Ratio (PSNR). The robustness is increased by reducing Bit Error Rate (BER). This proposed technique achieves high embedding capacity in high noise environment, high robustness when compared to conventional Quantization Index Modulation (QIM) methods.