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Vision, Image and Signal Processing, IEE Proceedings -

Issue 1 • Date Feb 2003

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Displaying Results 1 - 9 of 9
  • Shape based leaf image retrieval

    Page(s): 34 - 43
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (623 KB)  

    The authors present an efficient two-stage approach for leaf image retrieval by using simple shape features including centroid-contour distance (CCD) curve, eccentricity and angle code histogram (ACH). In the first stage, the images that are dissimilar with the query image are first filtered out by using eccentricity to reduce the search space, and fine retrieval follows by using all three sets of features in the reduced search space in the second stage. Different from eccentricity and ACH, the CCD curve is neither scaling-invariant nor rotation-invariant. Therefore, normalisation is required for the CCD curve to achieve scaling invariance, and starting point location is required to achieve rotation invariance with the similarity measure of CCD curves. A thinning-based method is proposed to locate starting points of leaf image contours, so that the approach used is more computationally efficient. Actually, the method can benefit other shape representations that are sensitive to starting points by reducing the matching time in image recognition and retrieval. Experimental results on 1400 leaf images from 140 plants show that the proposed approach can achieve a better retrieval performance than both the curvature scale space (CSS) method and the modified Fourier descriptor (MFD) method. In addition, the two-stage approach can achieve a performance comparable to an exhaustive search, but with a much reduced computational complexity. View full abstract»

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  • Side-match tree-structured vector quantiser for image progressive coding

    Page(s): 6 - 13
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    The balanced tree-structured vector quantiser is the traditional method of achieving image progressive coding. During image progressive coding, an image is decoded step-by-step in a decoder. The author proposes an unbalanced tree-structured vector quantiser to perform image progressive coding for a given series of rate thresholds. Side-match vector quantisation and its variants have been proposed to reduce the bit rate in image coding. The tree-structured vector quantiser and the side-match vector quantiser are combined to perform image progressive coding, achieving a better coding quality than that obtained using only the tree-structured vector quantiser at the same bit rate. View full abstract»

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  • Image extraction in DCT domain

    Page(s): 20 - 27
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (579 KB)  

    More and more digital images are being stored in compressed formats, among which the format using discrete cosine transform (DCT) coefficients is widely adopted (JPEG, MPEG, H.263 etc). To exploit those successful image processing techniques developed in the pixel domain, the authors propose a fast image extraction algorithm to allow images to be extracted directly from compressed DCT coefficients without full decompression. In the proposed technique the extracted images retain quality comparable with that of fully decoded images. However, the computing cost and the storage expense incurred by the proposed algorithm are very much lower than the costs of full decompression. The experiments also demonstrate that the proposed algorithm has tremendous potential in that all existing image processing techniques developed in the pixel domain can be directly applied to compressed images, without involving full decompression. View full abstract»

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  • New irregular sampling coding method for transmitting images progressively

    Page(s): 44 - 50
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (606 KB)  

    Transmitting images over channels of low capacity is an important issue relating to networks. The authors propose a new progressive image transmission (PIT) method based on the irregular sampling coding scheme. In the proposed method, the original image is first sampled using the irregular sampling scheme and the resulting samples are divided into several segments for the purpose of progressive image transmission. Therefore, each segment of the samples is further encoded and then transmitted to the receiver in each phase. At the receiver, the well known four-nearest-neighbour (4NN) algorithm is employed to reconstruct the rough image during each phase. According to the experimental results, the image quality is better in each transmission phase than the image quality for the related methods, i.e. FRM, TSVQ and SMTSVQ. Moreover, in the first phase, the difference in PSNR between this method and SMTSVQ is up to 2.8 dB. Therefore, the proposed method is more effective than the other methods described previously. View full abstract»

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  • Enhancement algorithm for nonlinear context-based predictors

    Page(s): 15 - 19
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (377 KB)  

    The authors propose a bicandidate algorithm (BCA) to enhance the prediction accuracy of nonlinear context-based predictors, such as the MED predictor (used by LOCO-I/JPEG-LS) and the GAP predictor (used by CALIC). The BCA provides two predictive values to be selected (i.e. there are two candidates), and only part of the selection should be indexed. To test the performance of the BCA, it is applied to the enhancements of the MED predictor and the GAP predictor. According to experimental results, both the enhanced predictors perform better in prediction accuracy (evaluated by the first-order entropy) at an average improvement rate of 2.8%, and the enhanced MED predictor outperforms the modified MED predictor proposed by Jiang et al. (2000) and the 'soft' predictors proposed by Estrakh et al. (2001). The predictors enhanced by BCA remain at similar complexity levels and the application of BCA is relatively simple. View full abstract»

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  • Experimental 3-D digital TV studio

    Page(s): 28 - 33
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (431 KB)  

    The Michelangelo Project at the University of Glasgow has developed an experimental three-dimensional television studio. This uses 24 video cameras and parallel computers to capture moving three-dimensional models of human actors. This allows the capture in real time of the appearance and three-dimensional positions of a human actor. It does this using stereo imaging techniques that have been under development at the University of Glasgow for several years. The development of the studio has thrown up many technical problems which are still to be fully resolved, nonetheless it is already producing convincing animated sequences. View full abstract»

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  • Symmetric prefilters for multiwavelets

    Page(s): 59 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (457 KB)  

    When applying discrete multiwavelets, prefiltering is necessary because the initial multiscaling coefficients cannot be trivially derived from the samples of scalar signals. There have been many studies on the design of prefilters, and one main approach is to use a superfunction. The idea is to construct a low-pass function from the multiscaling functions that inherits their approximation power for scalar signals. However, none of the existing prefilters give linear phase combined filters, which is important for many practical applications. The authors analyse the conditions on which the prefilters and the combined filters are symmetric. A method is proposed for the design of good multiwavelet prefilters that allow the superfunction to be symmetric, satisfying the Strang-Fix conditions and the resulting combined filters are linear phase. Design examples using DGHM and Chui-Lian multiwavelets are given. View full abstract»

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  • Extension of proposal of standards for intelligibility tests of Chinese speech: CDRT-tone

    Page(s): 1 - 5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (419 KB)  

    The published Chinese diagnostic rhyme test (CDRT) has been proposed as a standard method for evaluating the intelligibility of coded, synthesised or distorted Chinese speech over wired or wireless voice channels in a communication system. Inheriting the philosophy of the English context DRT test, the CDRT only assessed six groups of phonetic attribute distortion. However, pitch distortion is a highly important element for evaluating intelligibility of Chinese speech, which is characterised by Chinese tones, an important element of Chinese language which is absent in western languages. An extension to the CDRT named 'CDRT-tone' for the intelligibility test of Chinese tones is proposed. The relative features of Chinese tones are outlined and the principles of choosing phonetic units for the proposed standard, CDRT-tone, are presented. Then the validity of the CDRT-tone is discussed. Finally, CDRT-tone was applied to evaluate the pitch performance of the GSM regular pulse excitation with a long-term prediction (RPE-LTP) coding algorithm. View full abstract»

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  • DWT-based high-capacity blind video watermarking, invariant to geometrical attacks

    Page(s): 51 - 58
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (565 KB)  

    The paper describes a high-capacity blind video watermarking system invariant to geometrical attacks such as shift, rotation, scaling and cropping. A spatial domain reference watermark is used to obtain invariance to geometric attacks by employing image registration techniques to determine and invert the attacks. A second, high-capacity watermark, which carries the data payload, is embedded in the wavelet domain according to a human visual system model. This is protected by a state-of-the-art error correction code (turbo code). For a false detection probability of 10-8, the proposed system is invariant to scaling up to 180%, rotation up to 70°, and arbitrary aspect ratio changes up to 200% on both axes. Furthermore, the system is virtually invariant to any shifting, cropping, or combined shifting and cropping. The system is also robust to MPEG2 compression, even when combined with shifting and cropping. View full abstract»

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