Said Nader-Esfahani

Amin Banitalebi-Dehkordi, Mehdi Banitalebi-Dehkordi, Jamshid Abouei et al.

Digital watermarking is extensively used in ownership authentication and copyright protection. In this paper, we propose an efficient thresholding scheme to improve the watermark embedding procedure in an image. For the proposed algorithm, watermark casting is performed separately in each block of an image, and embedding in each block continues until a certain structural similarity threshold is reached. Numerical evaluations demonstrate that our scheme improves the imperceptibility of the watermark when the capacity remains fix, and at the same time, robustness against attacks is assured. The proposed method is applicable to most image watermarking algorithms. We verify this issue on watermarking schemes in Discrete Cosine Transform (DCT), wavelet, and spatial domain.

Amin Banitalebi, Said Nader-Esfahani, Alireza Nasiri Avanaki

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.