Hector Perez-Meana

A hybrid active noise cancelling with secondary path modeling

This paper presents a hybrid active noise cancelling (ANC) system, to overcome the acoustic feedback present in most feedforward ANC system, together with an on line secondary path estimation scheme. The ANC system provides a suitable solution to two important problems present in most ANC systems. The acoustic feedback is reduced using two FIR adaptive filters with feedforward and feedback configurations, respectively; while the secondary path modeling is carried out using a modification of the on line estimation method proposed by Akhtar. Computer simulation results show that the combination of the feedback and feedforward stages provides a fairly good acoustic feedback cancellation, while the secondary path estimation method performs fairly well, providing both a fairly good noise cancellation performance.

Watermarking-based image authentication with recovery capability using halftoning technique

In this paper two watermarking algorithms for image content authentication with localization and recovery capability of the tampered regions are proposed. In both algorithms, a halftone version of the original gray-scale image is used as an approximated version of the host image (image digest) which is then embedded as a watermark sequence into given transform domains of the host image. In the first algorithm, the Integer Wavelet Transform (IWT) is used for watermark embedding which is denominated WIA-IWT (Watermarking-based Image Authentication using IWT), while in the second one, the Discrete Cosine Transform (DCT) domain is used for this purpose, we call this algorithm WIA-DCT (Watermarking-based Image Authentication using DCT). In the authentication stage the tampered regions are detected using the Structural Similarity index (SSIM) criterion, which are then recovered using the extracted halftone image. In the recovery stage, a Multilayer Perceptron (MLP) neural network is used to carry out an inverse halftoning process to improve the recovered image quality. The experimental results demonstrate the robustness of both algorithms against content preserved modifications, such as JPEG compression, as well as an effective authentication and recovery capability. Also the proposed algorithms are compared with some previously proposed content authentication algorithms with recovery capability to show the better performance of the proposed algorithms.

Data hiding in audio signal using Rational Dither Modulation

A data hiding system in audio signals based on a Rational Dither Modulation is proposed, which hides information in the Modulated Complex Lapped Transform (MCLT) domain. The proposed system is able to hide around of 689bits per second, while keeping a CD-quality audio signal. Objective and subjective evaluations show robustness to classical attacks and transparency to the Human Auditory System (HAS), respectively. Comparison results, in similar conditions, with some other algorithms reported in the literature are also provided.

Digital Video Watermarking in DWT Domain Using Chaotic Mixtures

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 owners 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.

Transcoding resilient video watermarking scheme based on spatio-temporal HVS and DCT

Video transcoding is a legitimate operation widely used to modify video format in order to access the video content in the end-users devices, which may have some limitations in the spatial and temporal resolutions, bit-rate and video coding standards. In many previous watermarking algorithms the embedded watermark is not able to survive video transcoding, because this operation is a combination of some aggressive attacks, especially when lower bit-rate coding is required in the target device. As a consequence of the transcoding operation, the embedded watermark may be lost. This paper proposes a robust video watermarking scheme against video transcoding performed on base-band domain. In order to obtain the watermark robustness against video transcoding, four criteria based on Human Visual System (HVS) are employed to embed a sufficiently robust watermark while preserving its imperceptibility. The quantization index modulation (QIM) algorithm is used to embed and detect the watermark in 2D-Discrete Cosine Transform (2D-DCT) domain. The watermark imperceptibility is evaluated by conventional peak signal to noise ratio (PSNR) and structural similarity index (SSIM), obtaining sufficiently good visual quality. Computer simulation results show the watermark robustness against video transcoding as well as common signal processing operations and intentional attacks for video sequences.

An Image Steganography Systems Based on BPCS and IWT

In this paper, an image steganography system is proposed, in which the data hiding (embedding) is realized in bit planes of subband wavelets coefficients obtained by using the Integer Wavelet Transform (IWT). To increase data hiding capacity while keeping the imperceptibility of the hidden data, the replaceable IWT coefficient areas are defined by a complexity measure used in the Bit-Plane Complexity Segmentation Steganography (BPCS). The proposed system shows a high data hiding capacity (more than 2 bpp in many case), while keeping a high fidelity of stegoimage (more than 35 dB of PSNR). To make the proposed system robust enough to some distortion caused by non-ideal communication channel, we introduce an Error Control Coding to the system, which can reduce the Bit Error Rate (BER) of extracted hidden data when the stegoimage receive some channel distortion.

Robust hybrid color image watermarking method based on DFT domain and 2D histogram modification

In this paper, we present a robust hybrid watermarking method applied to color images for authentication, which presents robustness against several distortions. Due to the different nature of common signal processing and geometrical attacks, two different techniques for embed a same watermark are used in this method. In the first one, the luminance component (Y) information is used to embed the watermark bit sequence into the magnitude of the middle frequencies of the Discrete Fourier Transform (DFT). In the second one, a selected region of 2D histogram composed by blue-difference and red-difference (Cb–Cr) chrominance components is modified according to the watermark bit sequence. The quality of the watermarked image is measured using the following well-known indices peak signal to noise ratio (PSNR), visual information fidelity (VIF) and structural similarity index (SSIM). The difference color of the watermarked image is obtained using the normalized color difference (NCD) measure. The experimental results show that the proposed method provides robustness against several geometric distortions, signal processing operations, combined distortions and photo editing. The comparison with the previously reported methods based on different techniques is also provided.

An Early Fire Detection Algorithm Using IP Cameras

The presence of smoke is the first symptom of fire; therefore to achieve early fire detection, accurate and quick estimation of the presence of smoke is very important. In this paper we propose an algorithm to detect the presence of smoke using video sequences captured by Internet Protocol (IP) cameras, in which important features of smoke, such as color, motion and growth properties are employed. For an efficient smoke detection in the IP camera platform, a detection algorithm must operate directly in the Discrete Cosine Transform (DCT) domain to reduce computational cost, avoiding a complete decoding process required for algorithms that operate in spatial domain. In the proposed algorithm the DCT Inter-transformation technique is used to increase the detection accuracy without inverse DCT operation. In the proposed scheme, firstly the candidate smoke regions are estimated using motion and color smoke properties; next using morphological operations the noise is reduced. Finally the growth properties of the candidate smoke regions are furthermore analyzed through time using the connected component labeling technique. Evaluation results show that a feasible smoke detection method with false negative and false positive error rates approximately equal to 4% and 2%, respectively, is obtained.

Robust watermarking method in DFT domain for effective management of medical imaging

In general, management of medical data is achieved by several issues of medical information such as authentication, security, integrity, privacy, among others. Because medical images and their related electronic patient record (EPR) data are stored separately; the probability of corruption of this information or their detachment from the corresponding EPR data could be very high. Losing data from the corresponding medical image may lead to a wrong diagnostic. Digital watermarking has recently emerged as a suitable solution to solve some of the problems associated with the management of medical images. This paper proposes a robust watermarking method for medical images to avoid their detachment from the corresponding EPR data in which the watermark is embedded using the digital imaging and communications in medicine standard metadata together with cryptographic techniques. In order to provide a high robustness of the watermark while preserving at the same time a high quality of the watermarked images, the generated watermark is embedded into the magnitude of the middle frequencies of the discrete Fourier transform of the original medical image. During the detection process, the watermark data bits are recovered and detected using the bit correct rate criterion. Extensive experiments were carried out, and the performance of the proposed method is evaluated in terms of imperceptibility, payload, robustness and detachment detection. Quantitative evaluation of the watermarked images is performed by using three of the more common metrics: the peak signal-to-noise ratio, structural similarity index and visual information fidelity. Experimental results show the watermark robustness against several of the more aggressive geometric and signal processing distortions. The receiver operating characteristics curves also show the desirable detachment detection performance of the proposed method. A comparison with the previously reported methods with similar purposes respect to the proposed method is also provided.

A sub-block-based eigenphases algorithm with optimum sub-block size

Several algorithms have been proposed for constrained face recognition applications. Among them the eigenphases algorithm and some variations of it using sub-block processing, appears to be desirable alternatives because they achieves high face recognition rate, under controlled conditions. However, their performance degrades when the face images under analysis present variations in the illumination conditions as well as partial occlusions. To overcome these problems, this paper derives the optimal sub-block size that allows improving the performance of previously proposed eigenphases algorithms. Theoretical and computer evaluation results show that, using the optimal block size, the identification performance of the eigenphases algorithm significantly improves, in comparison with the conventional one, when the face image presents different illumination conditions and partial occlusions respectively. The optimal sub-block size also allows achieving a very low false acceptance and false rejection rates, simultaneously, when performing identity verification tasks, which is not possible to obtain using the conventional approach; as well as to improve the performance of other sub-block-based eigenphases methods when rank tests are performed.