Two-Dimensional Filters What is this chapter about? Manipulation of images often entails omitting or enhancing details of certain spatial frequencies. This is equivalent to multiplying the Fourier transform of the image with a certain function that “kills” or modifies certain frequency components. When we do that, we say that wefilter the image, and the function we use is called a filter. This chapter explores some of the basic properties of 2D filters and presents some methods by which the oper