Sampling and the Nyquist rate
Aliasing can arise when you sample a continuous signal
or image
•Demo
applet
•occurs
when your sampling rate is not high enough to capture the amount
of detail in your image
•formally,
the image contains structure at different scales
–called
“frequencies” in the Fourier domain
•the
sampling rate must be high enough to capture the highest
frequency in the image
To avoid aliasing:
•sampling
rate > 2 * max frequency in the image
–i.e.,
need more than two samples per period
•This
minimum sampling rate is called the Nyquist rate