Digital image enhancement techniques can have a significant impact on the diagnostic quality of a radiographic image. Selection of an image enhancement technique is a function of image content and its attributes of interest. The diagnostic value of a radiographic image is commonly reduced by its intrinsic limitations as well as interference from unwanted signals. In this second article on radiographic image enhancement the Fourier transform, the most commonly used transformation method, is used to examine examples of methods for image enhancement, with particular emphasis on the removal or reduction of noise.