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In seabed surveillance, the nonlinearity of the sonar display, together with variations in brightness and contrast arising from variability in the stored sonar data, will have a direct effect on the visual discrimination of seabed features. The loss of information at the man-machine interface is due to environmental and instrumentation effects, and can be partially corrected for in real-time (i.e. at video frame rates) if the data is digitised and available for computer processing. Methods are described for normalising 2-D sonar data and for correcting for luminance compression in the electronic display. Experimental results for sidescan sonar indicate that statistical normalisation and display calibration by gamma-compensation provide a standardised presentation of data. The procedure improves both the visibility of seabed features and the reliability of visual search during routine surveillance.

A need exists for improving the current methods for ensuring the safety of ammunition fuzes. Accordingly the feasibility of using automatic techniques for the inspection of ammunition fuzes has been investigated. The investigation covered the following aspects. (1) The usefulness of image enhancement techniques for the improvement of the detectability of defects; (2) the feasibility of automatic recognition of defects: and (3) the merits and the practicability of using real-time radiography to replace the film-based system for fuze inspection. It may be concluded from the feasibility study that image qualities can be significantly enhanced for visual detection. When a defect can be characterised in terms of the intensity and geometrical factors of its radiographic images automatic identification of the defect also appears to be feasible. The assessment also indicated that the use of real-time radiography is now a practical proposition. Keywords: Pattern recognition; Image processing; Australia. (Author)