Abstract
This paper presents a novel reversible fragile
watermarking algorithm for hologram authentication. In the algorithm,
the watermark is embedded in the transform domain. The marked hologram
is then stored in the spatial domain with finite resolution level.
The resolution level is allowed to be pre-specified for attaining
different degrees of transparency. The algorithm is based on Hadamard
transform for both watermark embedding and extraction. The Hadamard
transform and its inverse can be operated by simple addition, subtraction
and shift operations. Due to the simplicity of the transform, a sufficient
condition on the resolution level of marked holograms is derived for
guaranteeing the reversibility of watermarking. In addition, from
the condition, it is also observed that the hiding capacity for reversible
watermarking increases with the resolution level. The proposed algorithm
therefore provides high flexibility for reversible watermarking allowing
transparency and hiding capacity to be varied by selecting different
resolution levels. Moreover, a novel scheme is presented for supporting
self-containedness for 3D object reconstruction without requiring
the delivery of additional files consisting of parameters for diffraction
computation. Because of its low degradation in transparency, the algorithm
is also able to operate in conjunction with the existing spatial domain
based reversible algorithms to further enhance the hiding capacity
while maintaining high visual transparency.
© 2014 IEEE
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