  Growth of the Internet and networked multimedia systems has emphasized the
need for copyright protection of the media. Media can be images, audio clips,
videos and etc. Digital watermarking is today extensively used for many
applications such as authentication of ownership or identification of illegal
copies. Digital watermark is an invisible or maybe visible structure added to
the original media (known as asset). Images are considered as communication
channel when they are subject to a watermark embedding procedure so in the case
of embedding a digital watermark in an image, the capacity of the channel
should be considered. There is a trade-off between imperceptibility, robustness
and capacity for embedding a watermark in an asset. In the case of image
watermarks, it is reasonable that the watermarking algorithm should depend on
the content and structure of the image. Conventionally, mean squared error
(MSE) has been used as a common distortion measure to assess the quality of the
images. Newly developed quality metrics proposed some distortion measures that
are based on human visual system (HVS). These metrics show that MSE is not
based on HVS and it has a lack of accuracy when dealing with perceptually
important signals such as images and videos. SSIM or structural similarity is a
state of the art HVS based image quality criterion that has recently been of
much interest. In this paper we propose a robust least significant bit (LSB)
watermarking scheme which is optimized for structural similarity. The watermark
is embedded into a host image through an adaptive algorithm. Various attacks
examined on the embedding approach and simulation results revealed the fact
that the watermarked sequence can be extracted with an acceptable accuracy
after all attacks.
