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IEE Proceedings E (Computers and Digital Techniques)

Volume 127, Issue 5, September 1980

Volumes & issues:

Volume 127, Issue 5

September 1980

Special issue on image restoration and enhancement
Conference report. 1980 conference on pattern recognition
Optimisation techniques for digital image reconstruction from their projections
  • Author(s): T.S. Durrani  and  C.E. Goutis
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 127, Issue 5, p. 161 –169
  • DOI:  10.1049/ip-e.1980.0038
  • Type: Article
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  • p. 161 –169 (9)
    A method is proposed for the digital reconstruction of images from their projections based on optimising specified performance criteria. The reconstruction problem is embedded into the framework of constrained optimisation and its solution is shown to lead to a relationship between the image and the one-dimensional Lagrange functions associated with each cost criterion.Two types of geometries (the parallel-beam and fan-beam systems) are considered for the acquisition of projection data and the constrained-optimisation problem is solved for both. The ensuing algorithms allow the reconstruction of multidimentional objects from one-dimensional functions only.For digital data a fast reconstruction algorithm is proposed which exploits the symmetries inherent in both a circular domain of image reconstruction and in projections obtained at equispaced angles. Computational complexity is significantly reduced by the use of fast-Fourier-transform techniques, as the underlying relationship between the available projection data and the associated Lagrange multipliers is shown to possess a block circulant matrix structure.
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Maximum entropy algorithm applied to image enhancement
Multiple bandpass filters in image processing
Assessment of scintigram quality
  • Author(s): P.F. Sharp ; R.B. Chesser ; D.B. Smith
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 127, Issue 5, p. 185 –192
  • DOI:  10.1049/ip-e.1980.0041
  • Type: Article
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  • p. 185 –192 (8)
    The application of standard psychophysical techniques to the measurement of the quality of noisy images is shown using examples taken from clinical radionuclide imaging. In clinical radionuclide imaging the distribution of a radiopharmaceutical injected into a patient is mapped in vivo by using a scintillation detector to record the emitted gamma rays. Areas of above or below average radiopharmaceutical concentration may indicate clinical abnormalities, such as tumours. As the images have only a few hundred photons/cm2, random (Poisson) fluctuations in intensity are large and may mask changes in radiopharmaceutical concentration. The quality of these images is assessed by using either the method of constant stimulus or signal-detection theory to measure an observer's ability to detect small changes in image intensity. The method of constant stimulus is used to compare analogue with digital images. It is shown that smaller changes in intensity can be detected on digital images than on the analogue ones. Signal detection theory is used to measure the effect of filtering on image quality. For a given rate of false positive responses, the filtered images produce a higher true positive response rate than for the unfiltered ones.
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Synthesis and enhancement of the radionuclide tomographic section
  • Author(s): R.W. Rowe ; P.E. Undril ; W.I. Keyes
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 127, Issue 5, p. 193 –196
  • DOI:  10.1049/ip-e.1980.0042
  • Type: Article
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  • p. 193 –196 (4)
    In principle, it is possible to perfectly reconstruct a two-dimensional density distribution from measurements of one-dimensional projections, subject to certain restrictions on the data, by using one of a number of analytical reconstruction techniques. The radionuclide tomographic section, a map of radiopharmaceutical concentration in a chosen plane of an object, is reconstructed from measurements of the radioactive emission detected at points exterior to the object. However, practical implementation of the procedure means that it is impossible to satisfy all the requirements of the theory, so that the image merely approximates to the original to a greater or lesser extent. We examine the nature and extent of the deviations from the theory and their effect on the reconstructed image; in particular, the problems of sampling, statistics, detector properties, collimation and attenuation are considered in turn. The principles involved in conventional attempts at overcoming major artefacts resulting from the various aberrations are outlined, together with the most significant effects of such corrective procedures. Finally, an improved, system-specific, iterative technique for restoration and enhancement, which we have used in conjunction with the Aberdeen Section Scanner, is described.
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Microprocessor-based interactive image-processing system
Command language for interactive image analysis
Clip 4 parallel processing system
  • Author(s): T.J. Fountain  and  V. Goetcherian
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 127, Issue 5, p. 219 –224
  • DOI:  10.1049/ip-e.1980.0045
  • Type: Article
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  • p. 219 –224 (6)
    A machine, Clip 4, is described, which is based on the ideas of parallel image processing developed at University College London. The major sections of the machine are outlined, including the processor array, which comprises 1152 custom-designed integrated circuits. A programming language has been developed and the application of the hardware/software system to a number of image-processing problems is shown. The processing speed of the system is indicated, and is typically several orders of magnitude better than moderately sized mainframe serial computers.
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Processing and synthesis of biological data

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