Nyquist Applet
•Shows “signal” wave rather than recognizable image
•High frequency represents
–areas of abrupt change in image (high contrast)
–Text and line drawings are high frequency,
•Low frequency represents
–Areas of gradual brightness or color change in image
–Gradients are low frequency
•Sampling below Nyquist limit creates aliases—high frequency inputs that masquerade as low frequency ones
http://www.cs.brown.edu/exploratories/freeSoftware/repository/edu/brown/cs/exploratories/applets/nyquist/nyquist_limit_guide.html