In recent years, much attention has been focussed on Mahalanobis distance(MD) that treat multidimensional information systems for pattern recognition,diagnosis and prediction. Dr.G.Taguchi developed and proposed the MTS method which uses Mahalanobis distance. This paper describes a new inspection method for U.S. dollar bills using the MTS method. In the study, the pixel values that show black and white color concentration were converted by Fourier transformation to obtain frequency spectrum data. This data was used to construct a Mahalanobis space for inspection. As a result, the time to construct the base space and the time to calculate the distance has been shortened and a higher inspection speed can now be expected.
