Real-time image processing of magneto-optic images for the Magneto-Optic/Eddy Current Imager (MOI)

The Magneto-Optic/Eddy Current Imager (MOI) is a nondestructive evaluation technique developed as an alternative to eddy current probes for the detection of cracks and corrosion on aircraft surfaces. The principles of this technique are a combination of eddy current excitation and magneto-optic imaging that yield real-time images of local magnetic fields associated with the induced currents. The magneto-optic images produced by the MOI, while sufficient, do contain noise that degrades the overall image quality. The noise appears as snake-like lines and is caused by the magnetic domain boundaries in the MOI's garnet sensor. The primary goal of this thesis is to develop real-time filtering algorithms to remove the unwanted serpentine noise present in the magneto-optic images. The benefits of removing this unwanted noise include the detection of smaller defects and increased probability of detection (POD) of a flaw. There are a number of requirements pertaining to the image enhancement algorithms including noise removal, edge preservation, low cost and high processing speed. As the inspections are preformed on-line, near real-time processing is a necessary condition to ensure that the inspector sees the filtered image instantaneously.