
4.1 Sampling Using an Array of Points
87
Thus we see that the picture in Fig. 5 after it is sampled and reconstructed
can look like the picture in Fig. 7. Note that the original periodic pattern in
Fig. 5 appears at a different frequency and orientation in Fig. 7, hence the
name aliasing for this effect. The frequency w
0
— w
1A
[(w
0
—
w
mn
) in a more
general case] is called the aliased spatial frequency. |
In the preceding discussion on aliasing, we examined a picture with a
pattern at a single spatial frequency vv
0
and it gave rise to a single aliased
frequency vv
0
—vv, ,. In practice, depending on the reciprocal vectors w
x
and
vv
2
and the regio ...