By Topic

Vision, Image and Signal Processing, IEE Proceedings -

Issue 6 • Date Dec 1996

Filter Results

Displaying Results 1 - 8 of 8
  • Object boundary location by region and contour deformation

    Page(s): 353 - 360
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1552 KB)  

    Many applications in image analysis need to distinguish an object from its surroundings. The `snake' method (Kass, 1987) is a well known method to solve such problems by locating the object boundary from an initial plan, but it has the limitation that the distance between the initial plan and the object boundary should be `very small'. The authors present a two-step method, which combines region and contour deformation, to locate the boundary of an object from a designated initial boundary plan. First, they propose a new deformable region model to represent an object, and use the model to locate the boundary of the object by region deformation. This step fills the gap between a fairly rough initial plan and the `snake' method. The resulting boundary is then used as the initial plan of a `snake' method to further refine the boundary. The results of the method are shown in simulated images and MRI images of brain tumour patients View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Minimax design of recursive digital filters with a lattice denominator

    Page(s): 377 - 382
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    The authors deal with the problem of minimax recursive digital filter design with a lattice structure for the denominator. The design problem is formulated so that the coefficients for the numerator and denominator of a recursive filter can be found by solving the best linear complex Chebyshev approximation (LCCA). A design technique based on the weighted least-squares algorithm previously proposed by one of the authors is then developed for solving the resulting LCCA problem. During the design process, this technique finds the tap coefficients for the numerator and the reflection coefficients for the denominator simultaneously. The stability of the designed recursive filter is ensured by incorporating an efficient stabilisation procedure to make all of the reflection coefficient values fall between -1 and +1. Computer simulations show that the proposed technique provides better design results than existing techniques View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Motion detection using the randomised Hough transform: exploiting gradient information and detecting multiple moving objects

    Page(s): 361 - 369
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1004 KB)  

    An algorithm to detect one moving object using the randomised Hough transform (RHT) has previously been proposed. This new nonmodel-based method, called motion detection using randomised Hough transform (MDRHT), was shown be to applicable to translational and rotational motion detection of one moving object. The basic, earlier version of the MDRHT utilises edge points only as its features. The MDRHT is extended to use both edge pixels and the intensity-gradient vector at edge pixels. Moreover, the MDRHT method is generalised to detect also multiple moving objects. The translational motion experiments with the variant of the technique using gradient information and coping with several moving objects give promising results in two-dimensional-motion detection and estimation, compared with the earlier version of the MDRHT View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fast algorithm for pseudodiscrete Wigner-Ville distribution using moving discrete Hartley transform

    Page(s): 383 - 386
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    A new fast algorithm is proposed to compute pseudodiscrete Wigner-Ville distribution (PDWVD) in real-time applications. The proposed algorithm uses the moving discrete Hartley transform to compute the Hilbert transform and thereby implements the PDWVD in real domain. The computational complexity of the proposed algorithm is derived and compared with the existing algorithm to compute the PDWVD View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Regular implementation algorithms of time domain aliasing cancellation

    Page(s): 387 - 392
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The authors propose two highly regular algorithms for realising the time domain aliasing cancellation (TDAC) technique. The first TDAC implementation, which is based on the fast discrete cosine transform, effectively adopts analysis and synthesis window functions in the transform structure. This implementation algorithm achieves the least computational complexity in TDAC processes. The second TDAC implementation, which extends Goertzel's concept, uses a simple selectable-fixed-coefficient second-order infinite impulse response (IIR) filter to recursively achieve multichannel audio encoding and decoding processes. With a properly selected coefficient, this recursive implementation achieves a lower round-off-error than the current fast implementations and the direct implementation in finite wordlength. In recently developed high quality consumer products, the first algorithm is suitable to be realised in digital signal processing chips and the second one will be a better choice for VLSI implementation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient classification and codebook design for CVQ

    Page(s): 344 - 352
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1972 KB)  

    An efficient block classification and a new codebook design algorithms for classified vector quantisation (CVQ) are presented. The classification method is particularly simple and suited for hardware or software implementation. For each nonshade block, a local threshold is computed and used to binarise the block. The binary block is then compared with a predefined set of binary edge templates to decide its nature. On the other hand, the codebook design algorithm generates the codevectors in a short time, while providing considerable computational savings. It only uses the AC energy of the training set vectors to produce the codebook and the AC energy of an input block for its encoding. Subsequently, the actual codebook does not have to be present at the transmitter end. Good quality images, as measured by subjective and objective measures, are produced at bit rates in the range 0.64-0.87 bits per pixel (bpp) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Balanced realisations and model reduction of periodically time-varying state-space digital filters

    Page(s): 370 - 376
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The authors discuss balanced realisations and model reduction of periodically time-varying (PTV) state-space digital filters. Controllability and observability Grammians of PTV state-space digital filters are discussed. It is extremely interesting to notice that although PTV state-space digital filters can be implemented by using a group of time-invariant coefficient sets, controllability and observability Grammians cannot be evaluated independently by using any one set of these time-invariant coefficients. Also, important physical interpretations of controllability and observability Grammians are considered. Based on these analysis results, balanced realisations of PTV state-space digital filters are defined and a synthesis method for balanced realisations is proposed. As one application of balanced realisations, a reduced-order model of a PTV state-space digital filter can be obtained by taking a subsystem of balanced realisation of the PTV state-space digital filter. Finally, a numerical example is given to illustrate the balanced model reduction procedure View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Image coding by multistep, adaptive flux interpolation

    Page(s): 337 - 343
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1124 KB)  

    The authors describe and discuss the new technique, multistep adaptive flux interpolation (MAFI), and its application to image data for coding. When applied to an image, MAFI produces an output which is also in an image form, but which has a more uniform feature density and a greatly reduced size. MAFI warps the input image by removing those rows and columns which contain a majority of redundant pixels. The side information required for reconstruction is minimal, and the image can be further compressed using conventional coders, making the compression ratio even higher. Because of its warped nature, the MAFI output's statistics are also more consistent with the properties assumed by block-based discrete cosine transform (DCT) methods View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.