Sampling and the Nyquist rate
Aliasing can
arise when you sample a continuous signal or image
•occurs when your sampling rate is not high enough to
capture the amount of detail in
your image
•Can give you the wrong signal/image—an alias
•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
–said another way: ≥ two samples per cycle
•This minimum sampling rate is called the Nyquist rate
