Didier Nicholson

JPEG 2000 backward compatible error protection with Reed-Solomon codes

In this paper, a backward compatible header error protection mechanism is described. It consists of the addition of a dedicated marker segment to a JPEG 2000 codestream, that will contain the error correction data generated by a block error correction code (e.g. a Reed Solomon code). This mechanism allows leaving the original data intact, hence providing backward compatibility with the already standardised JPEG 2000. Neither side information from higher level, nor extra signalling encapsulation is needed, as the required information is directly embedded in the codestream and also protected. Finally, it is shown how this mechanism can be used for perform unequal error protection of the whole JPEG 2000 stream.

JPWL: JPEG 2000 for Wireless Applications

In this paper, we present the current status of the JPWL standardization work item. JPWL is an extension of the JPEG 2000 baseline specification in order to enable the efficient transmission of JPEG 2000 codestream over an error-prone network. In particular, JPWL supports a set of tools and methods for error protection and correction such as Forward Error Correcting (FEC) codes, Unequal Error Protection (UEP), and data partitioning and interleaving. We then evaluate the performance of the JPWL Error Protection Block (EPB) tool. We consider two configurations of EPB: to protect the Main and Tile-part headers, or to protect the whole codestream using UEP. Experimental results show a significant quality improvement when using EPB compared to baseline JPEG 2000.

JPWL - an extension of JPEG 2000 for wireless imaging

In this paper, we present an overview of the JPWL standardization activity. JPWL is an extension of JPEG 2000 for the efficient transmission of JPEG 2000 images over an error-prone wireless network. More specifically, JPWL supports a set of tools for error protection and correction, including forward error correcting codes (FEC), unequal error protection (UEP), data partitioning and interleaving

Offline quality monitoring for legal evidence images in video-surveillance applications

Video-surveillance attracted an important research effort in the last few years. Many works are dedicated to the design of efficient systems and the development of robust algorithms. video compression is a very important stage in order to ensure the viability of video-surveillance systems. However, it introduces some distortions decreasing significantly the detection, recognition and identification tasks for legal investigators. Fortunately, an important effort is made in terms of standard definition for video-surveillance in order to achieve to a complete interoperability. However, quality issues are still not addressed in an appropriate way. Investigators are often facing the dilemma of selecting the best match (legal evidence) of the targeted object in the video-sequence. In this paper, we propose an offline quality monitoring system for the extraction of most suitable legal evidence images for video-surveillance applications. This system is constructed around three innovative parts: First, a robust tracking algorithm based on foveal wavelet and mean shift. Second, a no-reference quality metric based on sharpness feature. Finally, a super-resolution algorithm allowing to increase the size of the tracked object without using any information outside the image itself. The combination of the proposed algorithms allowed the construction of a quality monitoring system increasing significantly the efficiency of the legal evidence image extraction.

Statistical motion vector analysis for object tracking in compressed video streams

Compressed video is the digital raw material provided by video-surveillance systems and used for archiving and indexing purposes. Multimedia standards have therefore a direct impact on such systems. If MPEG-2 used to be the coding standard, MPEG-4 (part 2) has now replaced it in most installations, and MPEG-4 AVC/H.264 solutions are now being released. Finely analysing the complex and rich MPEG-4 streams is a challenging issue addressed in that paper. The system we designed is based on five modules: low-resolution decoder, motion estimation generator, object motion filtering, low-resolution object segmentation, and cooperative decision. Our contributions refer to as the statistical analysis of the spatial distribution of the motion vectors, the computation of DCT-based confidence maps, the automatic motion activity detection in the compressed file and a rough indexation by dedicated descriptors. The robustness and accuracy of the system are evaluated on a large corpus (hundreds of hours of in-and outdoor videos with pedestrians and vehicles). The objective benchmarking of the performances is achieved with respect to five metrics allowing to estimate the error part due to each module and for different implementations. This evaluation establishes that our system analyses up to 200 frames (720x288) per second (2.66 GHz CPU).

Extrinsic distortion based source-channel allocation for wireless JPEG2000 transcoding systems

In this paper, we propose an extrinsic distortion-based source-channel allocation for JPWL transcoding systems. The distortion based approach is possible thanks to the extrinsic distortion estimation using information contained in the compressed bitstream. The proposed estimation method gives a coarse grain estimator of the true distortion, but keeping the same relative order of magnitude for distortion. Although coarse, this estimation can be used efficiently in a distortion based source-channel allocation strategy. Simulation results are provided in the context of JPEG2000 bitstream wireless transmissions using JPWL tools.

Technologies for multimedia and video surveillance convergence

In this paper, we present an integrated system for video surveillance developed within the European IST WCAM project, using only standard multimedia and networking tools. The advantages of such a system, while allowing cost reduction and interoperability, is to benefit from the fast technological evolution of the video encoding and distribution tools.

WCAM: smart encoding for wireless surveillance

In this paper, we present an integrated system for smart encoding in video surveillance. This system, developed within the European IST WCAM project, aims at defining an optimized JPEG 2000 codestream organization directly based on the semantic content of the video surveillance analysis module. The proposed system produces a fully compliant Motion JPEG 2000 stream that contains regions of interest (typically mobile objects) data in a separate layer than regions of less interest (e.g. static background). First the system performs a real-time unsupervised segmentation of mobiles in each frame of the video. The smart encoding module uses these regions of interest maps in order to construct a Motion JPEG 2000 codestream that allows an optimized rendering of the video surveillance stream in low bandwidth wireless applications, allocating more quality to mobiles than for the background. Our integrated system improves the coding representation of the video content without data overhead. It can also be used in applications requiring selective scrambling of regions of interest as well as for any other application dealing with regions of interest.

Seamless wireless networking for video surveillance applications

The EU FP6 WCAM (Wireless Cameras and Audio-Visual Seamless Networking) project aims to study, develop and validate a wireless, seamless and secured end-to-end networked audio-visual system for video surveillance and multimedia distribution applications. This paper describes the video transmission aspects of the project, with contributions in the areas of H.264 video delivery over wireless LANs. The planned demonstrations under WCAM include the transmission of H.264 coded material over 802.11b/g networks with TCP/IP and UDP/IP being employed as the transport and network layers over unicast and multicast links. UDP based unicast and multicast transmissions pose the problem of packet erasures while TCP based transmission is associated with long delays and the need for a large jitter buffer. This paper presents measurement data that have been collected at the WCAM trial site along with analysis of the data, including characterisation of the channel conditions as well as recommendations on the optimal operating parameters for each of the above transmission scenarios (e.g. jitter buffer sizes, packet error rates, etc.). Recommendations for error resilient coding algorithms and packetisation strategies are made in order to moderate the effect of the observed packet erasures on the quality of the transmitted video. Advanced error concealment methods for masking the effects of packet erasures at the receiver/decoder are also described.

Monitoring image quality for security applications

This work is focusing on the definition of a procedure for the qualification of coding schemes for video surveillance applications. It consists in developing and benchmarking tools that learn from the expertise of police and security department. This expertise is intended to be modeled thanks to a campaign of subjective measurement allowing to analyze the way they are using in performing the security tasks like face or license plate recognition, event detection and so on. The results of the previous test are used will be used to tune and to construct a hybrid metric based on basic artifacts detection due to compression and transmission.