Jose Juan Garcia-Hernandez

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.

Towards the construction of a benchmark for video watermarking systems: Temporal desynchronization attacks

Although several digital watermarking schemes have emerged as a solution to traditional copyright protection technologies, only a few benchmark suites, specialized in still images and audio, have been presented to measure the robustness and performance of these schemes. The aim of this paper is to single out the particularities in the way of evaluating the performance of video watermarking systems to generate a video watermarking benchmark framework specialized in temporal desynchronization attacks. In this way, this paper presents the most important temporal desynchronization attacks and performance measures for video watermarking systems.

On the Implementation of a Hardware Architecture for an Audio Data Hiding System

Data hiding systems have emerged as a solution against the piracy problem, particularly those based on quantization have been widely used for its simplicity and high performance. Several data hiding applications, such as broadcasting monitoring and live performance watermarking, require a real-time multi-channel behavior. While Digital Signal Processors (DSP) have been used for implementing these schemes achieving real-time performance for audio signal processing, custom hardware architectures offer the possibility of fully exploiting the inherent parallelism of this type of algorithms for more demanding applications. This paper presents an efficient hardware implementation of a Rational Dither Modulation (RDM) algorithm-based data hiding system in the Modulated Complex Lapped Transform (MCLT) domain. In general terms, the proposed hardware architecture is conformed by an MCLT processor, an Inverse MCLT processor, a Coordinate Rotation Digital Computer (CORDIC) and an RDM-QIM processor. Results of implementing the proposed hardware architecture on a Field Programmable Gate Array (FPGA) are presented and discussed.

Analysis of the impact of digital watermarking on computer-aided diagnosis in medical imaging

Medical images (MI) are relevant sources of information for detecting and diagnosing a large number of illnesses and abnormalities. Due to their importance, this study is focused on breast ultrasound (BUS), which is the main adjunct for mammography to detect common breast lesions among women worldwide. On the other hand, aiming to enhance data security, image fidelity, authenticity, and content verification in e-health environments, MI watermarking has been widely used, whose main goal is to embed patient meta-data into MI so that the resulting image keeps its original quality. In this sense, this paper deals with the comparison of two watermarking approaches, namely spread spectrum based on the discrete cosine transform (SS-DCT) and the high-capacity data-hiding (HCDH) algorithm, so that the watermarked BUS images are guaranteed to be adequate for a computer-aided diagnosis (CADx) system, whose two principal outcomes are lesion segmentation and classification. Experimental results show that HCDH algorithm is highly recommended for watermarking medical images, maintaining the image quality and without introducing distortion into the output of CADx.

FPGA-Based Flexible Hardware Architecture for Image Interest Point Detection

An important challenge in computer vision is the implementation of fast and accurate feature detectors, as they are the basis for high-level image processing analysis and understanding. However, image feature detectors cannot be easily applied in embedded scenarios, mainly due to the fact that they are time consuming and require a significant amount of processing power. Although some feature detectors have been implemented in hardware, most implementations target a single detector under very specific constraints. This paper proposes a flexible hardware implementation approach for computing interest point extraction from grey-level images based on two different detectors, Harris and SUSAN, suitable for robotic applications. The design is based on parallel and configurable processing elements for window operators and a buffering strategy to support a coarse-grain pipeline scheme for operator sequencing. When targeted to a Virtex-6 FPGA, a throughput of 49.45 Mpixel/s (processing rate of 161 frames per second of VGA image resolution) is achieved at a clock frequency of 50 MHz.

Efficient implementation of the RDM-QIM algorithm in an FPGA

The RDM-QIM algorithm has been proposed as a solution to the gain attack in QIM-based data hiding schemes. Several data hiding applications, such as broadcasting monitoring and live performance watermarking, requires a real-time multi-channel behavior. While Digital Signal Processors (DSP) have been used for implementing these schemes achieving real-time performance for audio signal processing, FPGAs offer the posibility of fully exploiting the inherent parallelism of this type of algorithms for more demanding applications. This letter presents an efficient FPGA implementation of RDM-QIM algorithm that overcomes a DSP-based implementation for more than two orders of magnitude and allows real-time multi-channel behavior.

Improving the security of Fallahpour’s audio watermarking scheme

The audio watermarking scheme recently proposed by Fallahpour in [1] is one of the schemes with highest payload published to date. In this letter a key-based security improvement is proposed for that scheme. It is achieved by adding a Pseudo-Random Number Sequence (PRNS) in the frequency domain to the data samples, before applying the insertion algorithm. Experimental results show that the proposed enhancement keeps the perceptual transparency and the robustness to all attacks originally reported by Fallahpours scheme and the payload is not significantly affected.

A low complexity time-scaling expansion algorithm of speech signals suitable for real time implementation

This paper presents the development and implementation of a variable rate time-scaling expansion system for speech signals, based on the pitch information, in which only the voiced segments are expanded, keeping the unvoiced and silence segments unchanged. The proposed system was first evaluated by computer simulation and then implemented on a digital signal processor (DSP). Time-domain, frequency-domain, mean opinion score (MOS) and diagnostic rhyme test (DRT) evaluations were done to test the actual performance of developed algorithm, which show that the proposed system allows improving the learning level of foreign language students as well as the understanding ability of elderly people. Objective tests also were carried out in order to probe similarity between the original and the expanded signals. Applying an iterative refinement of the C source code it was possible to obtain a real-time implementation. The current implemented algorithm requires 11 kwords program memory and about 9 million of floating point operations per second (MFLOPS).

Self-recovery scheme for audio restoration using auditory masking

Self-recovery schemes identify and restore tampering, using as a reference a compressed representation of a signal embedded into itself. In addition, audio self-recovery must comply with a transparency threshold, adequate for applications such as on-line music distribution or speech transmission. In this manuscript, an audio self-recovery scheme is proposed. Auditory masking properties of the signals are used to determine the frequencies that better mask the embedding distortion. Frequencies in the Fourier domain are mapped to the intDCT domain for embedding and extraction of reference bits for signal restoration. The contribution of this work is the use of auditory masking properties for the frequency selection and the mapping to the intDCT domain. Experimental results demonstrate that the proposed scheme satisfies a threshold of -2 ODG, suitable for audio applications. The efficacy of the scheme, in terms of its restoration capabilities, is also shown.