This dissertation describes the application of maximum entropy image restoration to envelope-detected ultrasonic sector scans. The maximum entropy restoration of the image of a point target (phantom) test object is shown to be superior to results obtained from the more familiar Wiener filter. The subsequent application of maximum entropy to an in-vivo clinical ultrasound image, however, illustrates the pitfalls associated with determining the relative merit of an ultrasonic image restoration technique from test object results alone. Since the resolution of sector scan images is substantially worse in the lateral (azimuthal) scan direction than the axial scan direction, the deconvolution filters described in this thesis were applied in the lateral direction only. The maximum entropy method is shown to have certain inherent advantages over linear frequency-domain techniques for the restoration of ultrasonic sector scan images. The positivity constraint inherent in the maximum entropy method is shown to produce restorations with substantially fewer oscillatory artifacts than those produced by Wiener filtering. In addition, the iterative nature of the maximum entropy algorithm is shown to be compatible with the restoration of the undersampled regions in the far field of sector scan images. The restoration of sector scan images is complicated by the spatially varying degradation associated with such images. A novel approach to the restoration of this class of image degradation is presented in this thesis. The widespread use of maximum entropy image restoration has been inhibited by the technique's demanding computational requirements. This problem can be alleviated by the use of high speed computer hardware, and the final chapters of this thesis describe the design and construction of a microcomputer-based array processor. The advantages inherent in the use of such hardware are demonstrated with reference to the maximum entropy restoration of ultrasonic images.

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Bibliography: pages 106-109. / This thesis describes techniques for the correction of spatial noise artifacts in a mercury cadmium telluride infrared camera system. The spatial noise artifacts are a result of nonuniformities within the infrared focal plane detector array. The techniques presented dispense with the need for traditional temperature references, and provide nonuniformity compensation by using only the statistics of the moving infrared scene and motion of the camera assembly for calibration. Frame averaging is employed, assuming that all of the detector pixels will eventually be irradiated with the same levels of incident flux after some extended period of time. Using a statistical analysis of the camera image data, the correction coefficients are re-calculated and updated. These techniques also ensure that the calculated coefficients continually track the variations in the dark currents as well as temperature changes within the dewar sensor cooling vessel. These scene-based reference free approaches to the calculation of compensation coefficients in the infrared camera are shown to be successful in compensating for the effects of fixed pattern spatial noise.

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