  A new local watermarking method based on histogram shifting has been proposed
in this paper to deal with various signal processing attacks (e.g. median
filtering, JPEG compression and Gaussian noise addition) and geometric attacks
(e.g. rotation, scaling and cropping). A feature detector is used to select
local areas for embedding. Then stationary wavelet transform (SWT) is applied
on each local area for denoising by setting the corresponding diagonal
coefficients to zero. With the implementation of histogram shifting, the
watermark is embedded into denoised local areas. Meanwhile, a secret key is
used in the embedding process which ensures the security that the watermark
cannot be easily hacked. After the embedding process, the SWT diagonal
coefficients are used to reconstruct the watermarked image. With the proposed
watermarking method, we can achieve higher image quality and less bit error
rate (BER) in the decoding process even after some attacks. Compared with
global watermarking methods, the proposed watermarking scheme based on local
histogram shifting has the advantages of higher security and larger capacity.
The experimental results show the better image quality as well as lower BER
compared with the state-of-art watermarking methods.
