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Nowadays, the administration of medical images can be compromised by several information security issues. Among others, a first problem consists in authenticating the source that originated the medical image and verifying that it corresponds to the correct patient; a second problem is aimed to avoid detachment between an electronic patient record and its corresponding images. A promising solution is the use of digital watermarking techniques applied to medical images considering in the design requirements of imperceptibility-robustness of the field of medical imaging. In this paper a digital watermarking method for an efficient administration of ultrasound images is proposed. To avoid the detachment between the record and images, we use an invisible watermarking in the frequency domain of the image. To authenticate the source of origin of the medical image, we use a visible-imperceptible watermarking in the spatial domain of the image. The experimental results show an efficient robustness and imperceptibility of the embedded watermark signals into the medical image. A comparison of performance with related works previously reported in the literature is included.

This paper presents a novel algorithm based on neural networks and fuzzy logic to generate membership functions and search an approximation of the optimal step-size for Normalized Least Mean Squares (NLMS) beamforming systems. The proposed method makes a new error curve, Error Ensemble Learning (EEL), based on the final estimated value of the adaptive algorithm´s mean-square-error. A fuzzy clustering method individually assigns membership values to each EEL curve coordinates. This information is fed into a neural network to generate membership functions for a fuzzy inference system. The final estimation of the optimal step-size is obtained using a group of Mamdani linguistic propositions and the centroid defuzzification method. Simulation results show that a useful approximation of the optimal step-size is obtained for different interference conditions; the evaluation results also show that a higher directivity is achieved in the radiation beam pattern.

This paper presents a public video watermarking algorithm, whose robustness depends on the embedding energy, which must be limited due to the degradation of video sequence caused by the same watermark signal. The proposed algorithm embeds a perceptually recognizable binary pattern, such as owner's logotype. Firstly the video sequences are segmented by each scene, and then the binary watermark pattern is embedded into Discrete Wavelet Transform (DWT) domain of the randomly selected scene blocks. To increase the security of the proposed scheme, the biary watermark pattern is mapped to a noise like binary pattern using a chaotic mixing method, before its embedding. Simulation results show the watermark imperceptibility and robustness against several attacks, such as noise contamination, frame dropping, frame averaging and frame swapping; the evaluation results also show that the extracted watermark pattern is sufficiently clear, although the watermarked video sequence may suffered several attacks.

Watermarking is considered as a desirable alternative for copyright protection of digital materials such as images, video and audio. Two kinds of watermarking algorithms are usually used: the watermarking algorithms using pseudorandom patterns and those using visual recognizable patterns. The main advantage of watermarking algorithms embedding a visual recognizable pattern, which can be the owner or provider logotype, is that after the extraction process the pattern can be visually recognized and then identified. In general the visual recognizable patterns has a large impact and less ambiguity during the copyright claim process as compared with the random patterns, however the amount of information required by the visual recognizable pattern is much larger than the amount of information required by the pseudorandom one, and then to achieve imperceptibility and robustness of the watermark is more difficult. This paper proposes a discrete wavelet transform (DWT) based watermark embedding algorithm for visual recognizable pattern which uses the relation between the human visual system and the DWT for embedding the watermark is such way that it becomes imperceptible and robust. Evaluation results show the desirable features of proposed scheme.