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4 Digitization
In the next two sections, we will discuss two different approaches to picture
sampling. In the first approach, the samples are the values of the picture
function (gray levels) at a discrete array of points, and we discuss the constraints
that a picture must satisfy for this type of sampling to be adequate. In the
second approach, the picture function is expanded in terms of orthonormal
functions, and the coefficients of expansion are the samples.
4.1 SAMPLING USING AN ARRAY OF POINTS
We will now present the theory of a sampling technique in which the
samples are the gray levels of the picture at an array of points. Before