Browsing by Subject "Digital Image Processing"

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    Fixed pattern noise compensation in a mercury cadmium telluride infrared focal plane array
    (1998) Reddy, Praven; De Jager, Gerhard
    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.