International Journal of Image and Graphics

In this paper we introduce and develop a framework for visual data-hiding technologies that aim at resolving emerging problems of modern multimedia networking. First, we introduce the main open issues of public network security, quality of services control and secure communications. Secondly, we formulate digital data-hiding into visual content as communications with side information and advocate an appropriate information-theoretic framework for the analysis of different data-hiding methods in various applications. In particular, Gel'fand-Pinsker channel coding with side information at the encoder and Wyner-Ziv source coding with side information at the decoder are used for this purpose. Finally, we demonstrate the possible extensions of this theory for watermark-assisted multimedia processing and indicate its perspectives for distributed communications.

In this paper, we propose an improved autocorrelation function (ACF)-based watermarking that is robust against combined geometric and removal attacks. ACF-based watermarking is known to be effective against geometric attacks. In this watermarking scheme, both the embedded watermark and autocorrelation peaks of the watermark should survive a variety of attacks. However, the autocorrelation peaks are not strong enough. The proposed method improves the robustness of ACF-based watermarking by enhancing the strength of the autocorrelation peaks. Instead of the simple addition of a watermark to an image, the proposed watermark embedder uses the information of an original image more actively during the embedding process, so that the marked image has strong autocorrelation peaks. Experimental results show that the proposed scheme provides better robustness than conventional ACF-based watermarking against a variety of combined geometric-removal attacks.

Digital watermarking has been proposed for the protection of digital medias. This paper presents two watermarking algorithms for binary images. Both algorithms involve a blurring preprocessing and a biased binarization. After the blurring, the first algorithm embeds a watermark by modifying the DC components of the Discrete Cosine Transform (DCT), followed by a biased binarization, and the second one embeds a watermark by directly biasing the binarization threshold of the blurred image, controlled by a loop. Experimental results show the imperceptibility and robustness aspects of both algorithms.

Video watermarks must maintain picture quality and withstand image processing, and resolving the tradeoff between these conflicting requirements has been one of the central problems in research on video watermarking. This paper shows that watermarks are less perceptible where picture contents are moving and proposes a new criterion for measuring watermark imperceptibility from motion vectors and deformation quantities. It also proposes a watermarking method that uses this criterion to allocate watermarks to picture areas adaptively. Experimental evaluation showed that the proposed method reduces degradation in picture quality and that, for the same picture quality after MPEG encoding and decoding, between 30% and 40% more watermarks can be embedded, improving detection reliability after MPEG processing by an average of 9.5%. The proposed method would be most effective when used with MPEG encoders because they already have the necessary motion estimation functions.

In this paper, we propose a blind video data-hiding algorithm in DWT (discrete wavelet transform) domain. It embeds multiple information bits into uncompressed video sequences. The major features of this algorithm are as follows. (1) Development of a novel embedding strategy in DWT domain. Different from the existing schemes based on DWT that have explicitly excluded the LL subband coefficients from data embedding, we embed data in the LL subband for better invisibility and robustness. The underlying idea comes from our qualitative and quantitative analysis of the DWT coefficients magnitude distribution over commonly used images. The experimental results confirm the superiority of the proposed embedding strategy. (2) To combat temporal attacks, which will destroy the synchronization of hidden data that is necessary in data retrieval, we develop an effective temporal synchronization technique. Compared with the sliding correlation proposed in the existing algorithms, our synchronization technique is more advanced. (3) We adopt a new 3D interleaving technique to combat bursts of errors, while reducing random error probabilities in data detection by exploiting ECC (error correcting coding). The detection error rate with 3D interleaving is much lower than that without 3D interleaving when frame loss rate is below 50%. (4) Take a carefully designed measure in bit embedding to guarantee the invisibility of information. In experiments, we can embed a string of 402 bytes (excluding the redundant bits associated with ECC) in 96 frames of the CIF format sequence. The experimental results have demonstrated that the embedded information bits are perceptually transparent when the frames in the sequence are viewed either as still images or played continuously. The hidden information is robust to manipulations, such as MPEG-2 compression, scaling, additive random noise, and frame loss.

With the ambient use of digital images and the increasing concern on their integrity and originality, consumers are facing an emergent need of authenticating degraded images despite lossy compression and packet loss. In this paper, we propose a scheme to meet this need by incorporating watermarking solution into traditional cryptographic signature scheme to make the digital signatures robust to these image degradations. Due to the unpredictable degradations, the pre-processing and block shuffling techniques are applied onto the image at the signing end to stabilize the feature extracted at the verification end. The proposed approach is compatible with traditional cryptographic signature scheme except that the original image needs to be watermarked in order to guarantee the robustness of its derived digital signature. We demonstrate the effectiveness of this proposed scheme through practical experimental results.

The interest for multimedia contents authentication has recently increased. In particular watermarking-based authentication schemes seem to be offering some advantages with respect to classical cryptography tools (e.g. real content authentication, localization of manipulations, storage format independence, transparency to common signal processing, etc.). In this paper a simple and secure self recovery authentication algorithm which hides an image digest into some DWT subbands of the to be authenticated image is presented. This technique has been designed for video surveillance and/or remote sensing applications. The main goal of this approach is to detect possible malevolent object manipulations undergone by the image (object replacing and/or deletion) by means of a self recovery processing. This valuable characteristic has to be maintained also when an image is processed through an usual and friendly transformation like JPEG compression. Particular care is given to make the scheme robust against innocuous manipulations, and secure against forgery attempts. Experimental results are presented that demonstrate the good performance of the proposed system.

This paper presents methods for performing steganography and steganalysis using a statistical model of the cover medium. The methodology is general, and can be applied to virtually any type of media. It provides answers for some fundamental questions that have not been fully addressed by previous steganographic methods, such as how large a message can be hidden without risking detection by certain statistical methods, and how to achieve this maximum capacity. Current steganographic methods have been shown to be insecure against simple statistical attacks. Using the model-based methodology, an example steganography method is proposed for JPEG images that achieves a higher embedding efficiency and message capacity than previous methods while remaining secure against first order statistical attacks. A method is also described for defending against "blockiness" steganalysis attacks. Finally, a model-based steganalysis method is presented for estimating the length of messages hidden with Jsteg in JPEG images.

In this paper, we investigate the general problem of data hiding and propose an approach for effective cover noise interference rejection in oblivious applications. We first evaluate the performance in the commonly used direct sequence modulation approach where a low-power signal is embedded into the original cover signal. The optimal detection is derived and its performance is analyzed. Second, we study a novel approach in oblivious data hiding and evaluate its performance and compare it with existing algorithms. Both simulation studies and empirical data hiding results validate its efficiency in the multimedia oblivious applications.