Quantization index modulation-based image watermarking using digital holography

We propose a blind watermarking method where the watermark is a hologram itself. In the proposed approach, the quantized phase of the hologram is embedded into the wavelet-transformed host image using quantization index modulation. In the detection stage, wavelet transform of the watermarked image followed by a minimum distance decoder is used. The proposed method is blind since it requires only information about the quantizers and the parameters of the hologram recording process. The robustness of the proposed technique is tested against several attacks such as filtering, compression, occlusion, and cropping. Moreover, we discuss the effect of quantization of the hologram on the reconstruction quality. (c) 2006 Optical Society of America