Christian Chatellier

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As successor to JPEG, JPEG2000 aims to realize a very low bitrate. Although JPEG2000's rate distortion has been improved by approximately 30% against JPEG, as on most images compressed using overlapping transforms-based algorithms , one can notice visible spurious oscillations, or ringing artifacts, around the edges of a JPEG2000-compressed image. In this(More)
In this paper, we propose a joint source channel coding (JSCC) scheme to the transmission of fixed images for wireless communication applications. The ionospheric channel which presents some characteristics identical to those found on mobile radio channels, like fading, multipath and Doppler effect is our test channel. As this method based on a wavelet(More)
The purpose of this paper is to describe the results of a CDMA digital transmission simulation in terms of quality, based on deterministic modeling of the propagation channel. This modeling allows a fast computation of the channel Power Delay Profile (PDP), which is the common input of a digital transmission system. Thus, the harmful impact of the channel(More)
Among the latest events of the wireless revolution, the fast-growing of ZigBee as a standard for WSN (Wireless Sensors Networks) is certainly one of these. ZigBee and 802.15.4 had been proving in the last years that they can achieve the results that Wi-Fi had achieved for high bit-rate wireless LANs and some large reliable deployments are now in place(More)
Today's needs for low bitrates in data compression are responsible for the MPEG and ITU family of video coding standards' success. However, it is important to realize that such standards involve lossy compression. This means a reconstructed image sequence will contain degradations relative to the original, because information is discarded during(More)
In this article, we propose a new multi-resolution, geometry-driven error concealment method for missing data recovery on grey-level and color for any block-based compression schemes, such as JPEG or MPEG. It requires no extra redundancy bits nor source-destination interactions, as opposed to classical FEC/ARQ schemes. The reconstruction process consists in(More)
The aim of this work is to present a robust still-image transmission scheme and to show its performance when used on a mobile fading channel. After a review of the main physical effects induced by mobile fading channels and how to model them, we describe the WTSOM (Wavelet Transform Self-Organizing Map) image transmission scheme. In section 2, we describe a(More)
In this paper, we propose a new approach for noise removal on color image sequences, based on coupled spatial and temporal anisotropic diffusions. This approach consists in smoothing a sequence while keeping all discontinuities caused by edges and moving objects. Our approach is based on a low level detection of moving areas in a noisy sequence, in order to(More)