Presentation-oriented key-frames coding based on fractals

This paper focuses on the problem of key-frames coding and proposes a new promising approach based on the use of fractals. The summary, made of a set of key-frames selected from a full-length video sequence, is coded by using a 3D fractal scheme. This allows the video presentation tool to expand the video sequence in a "natural" way by using the property of the fractals to reproduce the signal at several resolutions. This feature represents an important novelty of this work with respect to the alternative approaches, which mainly focus on the compression ratio without taking into account the presentation aspect of the video summary. In devising the coding scheme, we have taken care of the computational complexity inherent in fractal coding. Accordingly, the key-frames are first wavelet transformed, and the fractal coding is then applied to each subband to reduce the search range. Experimental results show the effectiveness of the proposed approach

Performance analysis of fractal modulation transmission over fast-fading wireless channels

Fractal modulation schemes have been under investigation for signal transmission over time-varying channels due to their advantages in data transmission at different frequency bands. This allows for an efficient reception also when channel condition variations are present, by selecting the optimal frequency/time resolution based on the current channel condition. In this paper, we present a performance analysis of fractal modulation transmission over Rician fast-fading channels in the presence of AWGN. A quadrature transmission scheme is simulated and compared, in terms of error robustness, to a QAM transmission system. Performance analysis papers in literature do not consider, for fractal modulation systems, time-varying channels, which are quite important as they represent the main configuration for communication systems based on this modulation technique. The novelty of our paper lies on the comparison of a fractal modulation system to a QAM one (core of the OFDM modulation technology, extensively used in broadcasting) using a test-bed simulation environment where additive noise and fast fading are considered, as typical error sources for transmission over wireless channels. Several wavelet families for a fractal modulation scheme have been considered and performance for each one measured; results reported show the effectiveness of the fractal modulation paradigm and confirm its effective utilization in data broadcasting

A new approach to slow motion effect for digital TV broadcasting services

Slow motion replay of video sequences is a commercial feature for home video players, but also a special effect used in video production. At present, most techniques to perform digital slow motion are based on interpolation for generating additional intermediate frames. Mainly, interpolation is done through linear or cubic spline functions or by motion estimation/compensation applied either pixel by pixel, or by partitioning frames into blocks. This approach has drawbacks: above all, interpolation bears to fading effects. Purpose of this paper is to present a novel technique combining fractals and wavelets to obtain higher performance in slow motion display of digital video sequences. Active scene detection and video processing are used to reduce computational cost and improve visual quality. This method produces better results in terms of objective perceptual video quality comparing to state-of-the-art techniques

Mutual Image-Based Authentication Framework with JPEG2000 in Wireless Environment

Currently, together with the development of wireless connectivity, the need for a reliable and user-friendly authentication system becomes always more important. New applications, as e-commerce or home banking, require a strong level of protection, allowing for verification of legitimate users' identity and enabling the user to distinguis trusted servers from shadow ones. A novel framework for image-based authentication (IBA) is then proposed and evaluated. In order to provide mutual authentication, the proposed method integrates an IBA password technique with a challenge-response scheme based on a shared secret key for image scrambling. The wireless environment is mainly addressed by the proposed system, which tries to overcome the severe constraints on security, data transmission capability, and user friendliness imposed by such environment. In order to achieve such results, the system offers a strong solution for authentication, taking into account usability and avoiding the need for hardware upgrades. Data and application scalability is provided through the JPEG2000 standard and JPIP framework.</p

Reduced-reference quality estimation for rate control in 3D video multicasting

We propose a rate control scheme for multicast streaming scalable 3D video sequences over wireless ad-hoc networks. We consider 3D colour plus depth video sequences encoded with the Scalable Video Coding (SVC) model. The scheme is designed to maximize the overall quality of the decoded video as perceived at the user-side by resorting on a reduced-reference (RR) video-quality estimation approach. The rate control module runs an algorithm that sets the optimal video layer configurations to transmit to each destination node on the basis of the links' throughput, the video quality perceived at the user side and the topology of the network