MOI IMAGE ENHANCEMENT USING ELECTRONIC BACKGROUND REDUCTION (EBR)

摘要

PRI Research and Development Corporation (PRI) is developing a practical, real-time image processing method for field implementation with magneto-optic (MOI) imaging Systems, using a technique we call "electronic background reduction" (EBR). EBR minimizes image-background noise so that image-processing and feature-extraction techniques can be applied more successfully. The technique digitally averages the background using two sequential images-4he first image has a dark background with bright serpentine domains, while the second image has a bright background with dark (reversed) serpentine domains. The sequence of steps in forming an improved image are as follows: first, the magneto-optic sensor is "reset" (prior images erased) and CCD camera acquires an image field (without eddy-current excitation). Then the image of the defect (e.g., a crack) is generated using eddy-current excitation, and the second camera field is acquired. These two fields are summed and normalized. The dark and bright background from these two fields together with the bright and dark serpentine domains average to a nearly constant value. The result is an enhanced image of defects, with minimal image-background noise. PR' will demonstrate this new technique and highlight the improvement over conventional magneto-optic imaging.