TABLE OF CONTENTS Image capture takes us from the continuous-parameter real world in which we live to the discrete-parameter, amplitude quantized domain of the digital devices that comprise an electronic imaging system. The process of converting from a continuous-parameter image to one that is discrete-parameter i.e., consists of an array of numbers, is referred to as sampling. The meaning of the term scanning is somewhat less precise. Its common usage refers to the notion of sequential acquisition of data through some type of electro-mechanical motion. It is also used to refer to the process of converting a two-dimensional signal to a signal that is one-dimensional. The process of quantizing an image that is continuous in amplitude to one that takes on values from a finite set is called quantization. Examples illustrating the effect of quantization may be found in Chapter 1.1.
Sampling a continuous-space image g c(x, y) yields a discrete-space image
where the subscripts c,d denote, respectively, continuous-space and discrete-space, and X is the spacing between sample points, also called the pitch. However, it is also convenient to represent the sampling process using the 2D Dirac delta function ?(x,y). In particular, we have from the sifting property of the delta function that multiplication of g c(x,y) by a delta function centered at...
