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Vision, Image and Signal Processing, IEE Proceedings -

Issue 6 • Date 30 Dec. 2004

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Displaying Results 1 - 7 of 7
  • Entropy-based metrics for the analysis of partial and total occlusion in video object tracking

    Page(s): 487 - 497
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1059 KB)  

    Metrics measuring tracking reliability under occlusion that are based on mutual information and do not resort to ground truth data are proposed. Metrics for both the initialisation of the region to be tracked as well as for measuring the performance of the tracking algorithm are presented. The metrics variations may be interpreted as a quantitative estimate of changes in the tracking region due to occlusion, sudden movement or deformation of the tracked object. Performance metrics based on the Kullback-Leibler distance and normalised correlation were also added for comparison purposes. The proposed approach was tested on an object tracking scheme using multiple feature point correspondences. Experimental results have shown that mutual information can effectively characterise object appearance and reappearance in many computer vision applications. View full abstract»

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  • Colour quantisation technique based on image decomposition and its embedded system implementation

    Page(s): 511 - 524
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (4758 KB)  

    A new colour quantisation (CQ) technique and its corresponding embedded system realisation are introduced. The CQ technique is based on image split into sub-images and the use of Kohonen self-organised neural network classifiers (SONNC). Initially, the dominant colours of each sub-image are extracted through SONNCs and then are used for the quantisation of the colours of the entire image. The proposed CQ technique can use both colour components and spatial features, achieving better approximation of the final image to the spatial characteristics of the original one. In addition, for the estimation of the proper number of dominant image colours, a new algorithm based on the projection of the image colours into the first two principal components is proposed. The image split into sub-images offers reduction of the on-chip memory requirements and is suitable for embedded system (or system-on-chip) implementation of the most time-consuming part of the technique. Applying a systematic design methodology to the developed CQ algorithm, an efficient embedded architecture based on the ARM7 processor achieving high-speed processing and less energy consumption, is derived. View full abstract»

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  • Algorithms for compressing compound document images with large text/background overlap

    Page(s): 453 - 459
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2945 KB)  

    Two algorithms are presented for compressing image documents, with a high compression ratio for both colour and monochromatic compound document images. The proposed algorithms apply a new method of segmentation to separate the text from the image in a compound document in which the text overlaps the background. The segmentation method classifies document images into three planes: the text plane, the background (non-text) plane and the text's colour plane, each of which are processed using different compression techniques. The text plane is compressed using the pattern matching technique, called JB2. Wavelet transform and zerotree coding are used to compress the background plane and the text's colour plane. Assigning bits for different planes yields high-quality compound document images with both a high compression ratio and well presented text. The proposed algorithms greatly outperform two well known image compression methods, JPEG and DjVu, and enable the effective extraction of the text from a complex background, achieving a high compression ratio for compound document images. View full abstract»

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  • Digital fragile watermarking scheme for authentication of JPEG images

    Page(s): 460 - 466
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1308 KB)  

    It is a common practice in transform-domain fragile watermarking schemes for authentication purposes to watermark some selected transform coefficients so as to minimise embedding distortion. The author points out that leaving most of the coefficients unmarked results in a wide-open security gap for attacks to be mounted on them. A fragile watermarking scheme is proposed to implicitly watermark all the coefficients by registering the zero-valued coefficients with a key-generated binary sequence to create the watermark and involving the unwatermarkable coefficients during the embedding process of the embeddable ones. Non-deterministic dependence is established by involving some of the unwatermarkable coefficients selected according to the watermark from a nine-neighbourhood system in order to thwart different attacks, such as cover-up, vector quantisation and transplantation. No hashing is needed in establishing the non-deterministic dependence. View full abstract»

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  • Theory for fast and cost-effective frequency response estimation of systems

    Page(s): 467 - 479
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    Frequency response, and hence transfer function, estimation of systems is of vital importance in several engineering fields such as signal processing, communications, control, system modelling and identification. Any digital frequency response scheme with attractive features such as low cost, high speed, good accuracy and excellent noise and harmonic rejection capabilities will therefore be of great practical benefit to practitioners in the above-mentioned fields. The author reports on a new frequency response estimation theory, based on the concept of non-subtractively dithered quantisation, which endows the classical quadrature correlation-based frequency response estimation scheme with all the above-mentioned attractive features. A theoretical analysis of the estimation (bias and variance) accuracy of this technique is given. The theory is tested on a number of filters and under some stringent conditions characterised by the coarsest possible (1-bit) quantisation scheme and very noisy (low SNR) environments. Simulation results substantiate the proposed theory quite well, thus making the VLSI implementation of the proposed 1-bit estimation scheme on a chip an attractive proposition. View full abstract»

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  • Flexible, highly scalable, object-based wavelet image compression algorithm for network applications

    Page(s): 498 - 510
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1139 KB)  

    The authors propose a highly scalable image compression scheme based on the set partitioning in hierarchical trees (SPIHT) algorithm. The proposed algorithm, called highly scalable SPIHT (HS-SPIHT), adds the spatial scalability feature to the SPIHT algorithm through the introduction of multiple resolution-dependent lists and a resolution-dependent sorting pass. It keeps the important features of the original SPIHT algorithm such as compression efficiency, full SNR scalability and low complexity. The flexible bitstream of the HS-SPIHT encoder can easily be adapted to various resolution requirements at any bit rate. The parsing process can be carried out on-the-fly without decoding the bitstream by a simple parser (transcoder) that forms a part of a smart network. The HS-SPIHT algorithm is further developed for fully scalable coding of arbitrarily shaped visual objects. The proposed highly scalable algorithm finds applications in progressive web browsing, visual databases and especially in image transmission over heterogeneous networks. View full abstract»

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  • Pros and cons of fine granular scalability-based MPEG-2 compressed-domain processing

    Page(s): 480 - 486
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (746 KB)  

    The pros and cons of FGS-based MPEG-2 video transcoding are examined. An existing solution for elastic storage of media (Barrau, 2002) is reviewed. Its shortfalls in terms of picture drift are identified and addressed by means of proposing a modified transcoding architecture, which is then compared to SNR-based MPEG-2 multilayer transcoding. It is shown that the FGS-based MPEG-2 video transcoder has the advantage of simplified transcoding and decoding architectures. However, the SNR-based MPEG-2 transcoder is shown to produce higher quality reconstructed images with superior rate-distortion performance. View full abstract»

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