An Electronic Watermarking Technique for Digital Holograms in a DWT Domain

Digital hologram generated by a computer calculation is one of the most expensive contents and its usage is being expanded. Thus, it is highly necessary to protect the ownership of digital hologram. In this paper a spatial-domain and a frequency-domain electronic watermarking schemes were proposed. The spatial-domain scheme was only to compare the results to the ones from frequency-domain scheme and the frequency-domain scheme used 2-dimensional mallat-tree discrete wavelet transform. Both of them showed very high imperceptibility and quite high robustness against the attacks. Especially the MDWT-domain scheme was very high robustness such that the error ratio at the worst case was only 3%. Thus, we expect that it is used as a good watermarking scheme of digital hologram with high performance. But the spatial-domain scheme was turned out to be useless when data compression process is necessary after watermarking.