In order to represent large video collections in the form of key-frame summary on small screen devices, this paper exploits methodology of the visual attention modelling and rapid serial visual presentation. This approach results in an intuitive layout of efficiently generated video summaries. A robust real-time algorithm for key-frame extraction is presented. The system ranks importance of key-frame regions in the final layout by exploiting visual attention modelling. A final layout is created using an optimisation algorithm based on dynamic programming. Algorithm efficiency and robustness are demonstrated by comparing the results with the manually labelled ground truth.

In this paper we investigate the utilization of visual saliency maps for ROI-based video coding of video-telephony applications. Visually salient areas indicated in the saliency map are considered as ROIs. These areas are automatically detected using an algorithm for visual attention (VA) which builds on the bottom-up approach proposed by Itti et al. A top-down channel emulating the visual search for human faces performed by humans has been added, while orientation, intensity and color conspicuity maps are computed within a unified multi-resolution framework based on wavelet subband analysis. Priority encoding, for experimentation purposes, is utilized in a simple manner: Frame areas outside the priority regions are blurred using a smoothing filter and then passed to the video encoder. This leads to better compression of both Intra-coded (I) frames (more DCT coefficients are zeroed in the DCT-quantization step) and Inter coded (P, B) frames (lower prediction error). In more sophisticated approaches, priority encoding could be incorporated by varying the quality factor of the DCT quantization table. Extended experiments concerning both static images as well as low-quality video show the compression efficiency of the proposed method. The comparisons are made against standard JPEG and MPEG-1 encoding respectively.

Live football video is the major content genre in 3G mobile service. In this paper, we introduce a realtime general highlight detection algorithm based on attention analysis. It combines attention-related media modalities into role-based attention curves, namely video director, spectator and commentator, to track viewers' feeling against game content from media data. A series of linear temporal predictors are assumed from video data directly and employed to allocate strong attention changes, which are marked as scroll-back endpoints for mobile video skim. The advantages of our algorithm are that it avoids semantic uncertainty of game highlights and that it requires little training. We evaluated our approach using the test bed with full five games from different content suppliers to prove the robustness.

We approach image compression using an affine symmetric image representation that exploits rotation and scaling as well as the translational redundancy present between image blocks. It resembles fractal theory in the sense that a single prototypical block is needed to represent other similar blocks. Finding the optimal prototypes is not a trivial task particularly for a natural image. We propose an efficient technique utilizing independent component analysis that results in near-optimal prototypical blocks. A reliable affine model estimation method based on Gaussian mixture models and modified expectation maximization is presented. For completeness, a parameter entropy coding strategy is suggested that achieves as low as 0.14 bpp. This study provides an interesting approach to image compression although the reconstruction quality is slightly below that of some other methods. However the high frequency details are well-preserved at low bitrates, making the technique potentially useful in low bandwidth mobile applications.

The DVB-H standard allows broadcasting of audio and video content to mobile terminals that have to face strict requirements concerning computational load and power consumption. Given the already intensive effort required by the decoding of the H.264/AVC video data stream, it is important to implement low complexity strategies for the concealment of the data losses. They are likely to happen, given the error prone nature of the wireless environment. The aim is to provide an acceptable video quality to the final user, without strongly affecting the resources available to the mobile device.

In [1] we introduced a new real-time variable frame rate control scheme. It is based on the video jerkiness and it can be applied to both coding and transcoding. This scheme constantly traces the motion of the incoming video and automatically tunes the outgoing frame rate according to the level of jerkiness acceptable by the user.

This scheme has been conceived in the framework of mobile communications, which calls for an optimum use of both the available bandwidth and terminal resources.

In this paper we present a subjective assessment of our solution carried out in a professional laboratory suitably equipped. Towards this aim a group of non-expert users was asked to express their preference when watching side by side the same video coded at variable frame rate and at fixed frame rate. Results show that most of the times a variable frame rate control based on a dynamic bit/frame allocation scheme may substantially improve the video quality perceived by the users.

One of the main goals of watermarking is to optimize capacity while preserving high video fidelity. The perceptual adjustment of the watermark is mainly based on Watson Just Noticeable Difference (JND) model. Recently, it was proposed to improve Watson model using the classification blocks inherent to the encoder in a compressed stream. Although, the new model outperforms the previous one, especially in increasing the watermark power in textured blocks, it still underestimates JNDs at block's edges. This work presents a detailed comparison of these two models and proposes a new method that exploits the good characteristics of the two available models. In addition, experimental results on perceptibility are reported.

In this paper, we present a novel framework that serves adaptive sports video to mobile users. Our framework combines content-based sports highlights extraction and quality-domain video compression technologies in video server, capable of reducing wireless bandwidth consumption more effectively. We develop a robust replay-based highlights extraction method, and propose a content-based video streaming coding scheme to handle the problems of bandwidth and capacity of computation. To validate the practicality and effectiveness of our system, we conduct the experiments on several real soccer videos. The experimental results demonstrate the robustness of our highlights extraction method and more than 77.5% of the bandwidth consumption could be reduced.

Rate-Distortion Optimization (RDO) is a new feature of JVT H.264/AVC video encoder that enables a substantial enhanced efficiency with respect to all previous video coding standards. However, RDO causes a considerable increase in encoding computational complexity, proportional to the square of the search window size when the Full-Search motion estimation algorithm is applied. In this paper, a fast block-based predictive-recursive motion estimation algorithm is illustrated in combination with RDO algorithms. Extensive simulations show that, using the proposed algorithms, the time devoted to RDO is significantly reduced while keeping performance extremely close to JVT reference software JM8.6.

The Ultra-wideband (UWB) spread spectrum technology provides a unique platform for (integrated) communication services spanning a wide range of bit rates (from few kbit/s up to hundreds Mbit/s). The acceptance of the UWB technology worldwide is mainly related to coexistence issues with other existing narrowband and wideband systems sharing the spectrum with UWB.

In this paper, we present a proposal for a "detect and avoid" (DAA) procedure that UWB devices would use to mitigate interference to indoor broadband wireless communications services and ensure that the appropriate protection criteria are met.

We analyze the performance of an UWB system when the proposed procedure is applied. We assess the UWB system throughput and the time actually available to UWB for transmitting. We analyze the dependence of the UWB system performance on the DAA procedure parameters and on the characteristics of the victim system.