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Communications, Speech and Vision, IEE Proceedings I

Issue 3 • Date June 1990

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Displaying Results 1 - 10 of 10
  • Shift invariant neural net for machine vision

    Publication Year: 1990 , Page(s): 183 - 187
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (397 KB)  

    A multilayer network is described which is able to recognise simple shapes in a shift, size, and rotation invariant manner. The use of layers of units to smooth and then to shift the image eliminates the need for the very large numbers of cells which are often proposed in shift invariant networks. The network was trained using back-propagation and is not intended to be plausible as a model of biological vision at the level of cell and connection detail. Some interesting parallels with human vision are noted in the emergent behaviour of the network.<> View full abstract»

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  • IAL: a parallel image processing programming language

    Publication Year: 1990 , Page(s): 176 - 182
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (509 KB)  

    The authors describe a high-level programming language for image processing, called IAL (image algebra language). IAL has been designed for low-level image processing applications. It has been implemented on transputer networks. IAL provides mechanisms whereby a programmer can specify image processing operations algebraically on the complete image. The implementation automatically parallelises the program, distributes the image data and controls all interprocess communication. The language is based on image algebra (a mathematical notation developed specifically for low-level image processing at the University of Florida). They describe the features of the language and provide an outline of some of the strategies used in implementing it on a transputer network.<> View full abstract»

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  • Quantification of retinal damage during cardiopulmonary bypass: comparison of computer and human assessment

    Publication Year: 1990 , Page(s): 170 - 175
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1331 KB)  

    A comparison of retinal fluorescein angiograms taken before cardiopulmonary bypass with those taken just before the end of operation, has shown that microvascular occlusions can develop during operation. Quantification of the retinal damage in terms of the area of nonperfusion depends on careful examination by humans. Assessment of these areas is necessarily subjective and digital image analysis would be preferable to make the measurements more objective. Visual or automatic comparison of images is facilitated by prior geometrical alignment. A method for registering retinal images which has been used successfully on 65 image pairs is described. Techniques for automatically detecting changes in the microvascular structure are illustrated. Using a subset of 40 good quality image pairs, good agreement between computer detected occlusions and human assessment of nonperfusing areas is reported.<> View full abstract»

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  • Expansion of two-dimensional imaging apertures for resolution improvement in long-wavelength holography

    Publication Year: 1990 , Page(s): 157 - 162
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A method is described for improving resolution in long-wavelength holography by expanding the two-dimensional hologram aperture. Simulation results are presented to illustrate resolution improvements obtained when doubling the linear size of square apertures for imaging single-point, multiple-point and quasi-continuous objects in the presence of noise. A technique for improving the quality of images reconstructed from predicted holograms using a number of focus measures is described. Alternative strategies for reconstructing the two-dimensional holograms are discussed and their performance compared regarding prediction errors and noise. Data is supplied on CPU time usage for hologram expansion and reconstruction on a VAX-11/785 computer.<> View full abstract»

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  • Dynamic elastic image stretching technique applied to thermographic images

    Publication Year: 1990 , Page(s): 146 - 156
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (818 KB)  

    A method of automatically stretching a series of hand thermograms to a standard form is described. It is based on an elastic model which has the iterative and co-operative properties of relaxation labelling, while not requiring large storage space for label updating. At each iteration some of the mutual differences between image pairs are removed, making the association between the new pairs more reliable. The experiments described show that mismatches decrease with each iteration, and thus the reliability of both local and global matches is increased. The method is co-operative because a feature at one location influences decisions made in its surrounding area. Nearest neighbour relationships are used to derive local difference vectors between features. These vectors are combined in a weighted averaging scheme to produce corrected difference vectors which are then applied to an image to create a new image for further matching. An FFT based technique has been developed to enhance the efficiency of the corrected difference vector evaluation. The method has been found to be efficient and cost effective for 2-dimensional image matching.<> View full abstract»

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  • Image enhancement and analysis with reaction-diffusion paradigm

    Publication Year: 1990 , Page(s): 136 - 145
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (906 KB)  

    Used to model pattern development in biological and chemical systems, reaction-diffusion (RD) equations possess self-organising properties that are useful in processing many classes of images. The authors describe their use in processing two classes: images with quasi-zero-dimensional patterns (textures), and images with quasi-one-dimensional patterns (fingerprints). They present details of linear and nonlinear analysis of RD equations, outlining their pattern-forming principles. Details of how to engineer RD systems are presented, together with examples and parameter sets.<> View full abstract»

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  • Unification of image segmentation and edge detection

    Publication Year: 1990 , Page(s): 129 - 135
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (939 KB)  

    A method of simultaneous image segmentation and edge detection based on grey-level cooccurrence matrices is described. An analysis of the distributions within a cooccurrence matrix defines an initial pixel classification into both region and interior or boundary classes. Local consistency of pixel classification is enforced by minimising the entropy of local region and boundary information, where region information is expressed by conditional probabilities, estimated from the cooccurrence matrices, and boundary information by conditional probabilities which are determined a priori. The method robustly segments an image into homogeneous areas and generates an edge map. The technique extends easily to general edge operators; examples are given of the techniques applied to both synthetic and infrared imagery for the (1-1) and Canny edge operators. The results are compared with other techniques.<> View full abstract»

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  • Stream processing architecture for real-time implementation of perspective spatial transformations

    Publication Year: 1990 , Page(s): 123 - 128
    Cited by:  Patents (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    A system is presented which is capable of performing perspective spatial transformations at video rate, by means of a mapping function which can vary at frame rate. The mapping is implemented by two successive applications of a one-dimensional algorithm operating in scan-line order, using a framestore to store an intermediate image. A novel one-dimensional filtering algorithm provides a continuous mapping from source to destination coordinates, significantly reducing aliasing. Emphasis is placed on the design of a novel stream processing architecture which, coupled with an efficient pipelined coordinate generation system, provides single-cycle per output pixel performance.<> View full abstract»

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  • Octree-based modelling of computed-tomography images

    Publication Year: 1990 , Page(s): 118 - 122
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (421 KB)  

    The authors present a modelling technique based on octrees which builds a three-dimensional model from the scanned slices and then allows the production of arbitrarily sliced images and projections, volume calculations, etc. The Millar polyhedron is introduced as a new technique used to build the octree. It exploits the volume coherence in the image data in such a way that the octree nodes can be directly specified from its output. It is clearly demonstrated that the transputer approach can allow the production of a real-time system at lower cost. Experimental results indicate that the algorithms are inherently concurrent and are suited to implementation in a parallel processing environment such as that provided by the transputer. They also indicate the degree of data compression obtained by using the technique, compared with direct storage of the raw data.<> View full abstract»

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  • Maximum image restoration in nuclear medicine

    Publication Year: 1990 , Page(s): 163 - 169
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (606 KB)  

    The problem of image restoration from noisy measurements as encountered in nuclear medicine is considered. A model for the emission/detection process is introduced, which is based on the Poisson statistics of the emissions and a point-spread function for the imaging system. A new approach for treating the measurements is given, in which they are represented by a spatial noncausal interaction model before maximum entropy restoration, which describes the statistical dependence among the image values and their neighbourhood. The particular application of the algorithms presented relates to gamma-ray imaging systems, and is aimed at improving the resolution-noise-suppression product. Results for actual gamma camera data are presented and compared with more conventional techniques.<> View full abstract»

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