Frame Rate

• Because of a phenomenon called "persistence of vision," the human eye continues to comprehend a vision for a fraction of a second after it disappears. If a new image immediately appears in its place with objects in different positions, they appear to move. A continuing sequence of different images produces continuing motion. Movie, television and computer screens use this phenomenon to create images that appear to move. Each image presented to a screen is called a "frame." Movies typically show 24 frames per second and TV, 30. Frame rate, however, is often confused with refresh rate.
  
  

Refresh Rate

• A refresh rate should at least be the same as a frame rate or a multiple thereof to present a flowing picture. If you have a monitor that refreshes the screen 60 times per second, with a frame rate of 30, the screen simply presents the same image twice. When transferring movies to television, some producers use frame rate conversion. Developers of TV and computer monitors continue to experiment with frame and refresh rates to provide smoother flowing images with screens manufactured with newer technologies and materials.
  
  

Incorrect Rates

• Theoretically, the human eye can only perceive a picture changing at 30 times per second. But when frame and refresh rates are improperly coordinated with the type of screen, picture quality suffers. Too slow rates make the pictures jerky and too fast rates may cause eye fatigue. However, not all screens act the same. Cathode-ray tubes, liquid crystal displays, light-emitting diode displays and plasma screens all have different characteristics, but LCD screens are the most susceptible to problems with refresh rates.
  
  

LCD Screens

• A fast-moving picture on a LCD screen at with a 60 hertz refresh rate may have blurred colors on the edges. A slower moving picture may tend to jerk or judder. Some special effects from movies may not work. So, most development concentration for refresh rates concentrates on LCD technology. But, to confuse the issue, not all eyes see the problems equally. Computer monitor manufacturers offer the higher refresh rates as options on selected models, with the ability to return them to 60 hertz if the viewer so desires.