Holographic watermarking based on off-axis hologram and DWT

In this paper, a holographic watermark scheme is proposed by combining off-axis hologram with discrete wavelet transform (DWT). A pyramid shaped object is recorded as a digital hologram by using the off-axis setup. Due to the unique nature of the hologram, the object information can be reconstructed by using a portion (25%, 50% and 75%) of the total hologram size. These allow us to reduce the hologram file size. The hologram is then used as a watermarks image. We had demonstrated that the watermark perceptual quality and robustness increase by reducing the watermark file size. The watermarking is done by superposed the watermark into the wavelet captured host image. The evaluation of the proposed watermarking scheme tested on several attacks, i.e. noise, Gaussian filter and amplitude changing.