Application of Fourier Theory in Radiographic Image Analysis

Digital radiographic images are considered two-dimensional signals, where the signals are represented by gray value matrices. When such signals are properly presented in the form of surfaces, areas of large signal magnitude appear bright and areas of small magnitude appear dark. Fourier transforms of radiographic images transfer the signal from the spatial to the frequency domain, where each point in the frequency domain represents a particular frequency contained in the radiographic image. In the Fourier domain, low frequencies are related to the background of the radiographic image, while high frequencies represent edge details of the images. Fourier analysis is an important tool in radiographic image processing, which can be used to separate low and high frequency details of an image. In this paper, two-dimensional Fourier transforms of signals are used to analyze and improve radiographic images.