Application of Taguchi Methodology for Optimizing Test Parameters in Magneto‐Optic Imaging

The optimization of experimental parameters in an NDE test is extremely crucial making accept/reject decision about a test sample. For instance, in magneto‐optic imaging (MOI) defects are displayed as an analog video image that is interpreted by the inspector. Subtle images such as for small surface and subsurface defects may be difficult for the inspector to detect. Under these circumstances, digital image processing methods may assist the inspector to interpret the MOI images. The accept / reject decision for a test specimen is determined by observing the binary image obtained by thresholding the magnetic flux density distribution. The coefficient of skewness of the binary magneto‐optic (MO) image can be used for calculating the probability that the image contains a crack. The larger the skewness value, implies a larger likelihood of the presence of a crack. Several test parameters affect the skewness of binary MO image and hence the likelihood of the image containing a crack. The optimal set of test pa...