The refresh rate, also known as frame rate, indicates how many images are displayed in a unit of time. It is a characteristic variable for the flow of moving image sequences and for the flicker-free display. The repetition of images in rapid sequences is necessary to circumvent the inertia of the eye and to make the moving image display appear continuous. The number of frames per second (fps) is calculated from the frame rate.
- For television pictures and video, the PAL television standard works with 25 full frames per second and NTSC with 30 full frames. The fields have a frame rate of 50 Hz. Each frame is composed of two interlaced fields. This interlaced method doubles the frame rate and reduces flicker. 100 Hz technology is used for televisions, which further reduces flicker.
- Computer monitors, on the other hand, work with progressivescan, i.e. with continuous scanning, and guarantee freedom from flicker thanks to refresh rates of 60 Hz to 100 Hz. 85 Hz is recommended. The requirements for refresh rates are specified in the TCO guidelines. LCD displays and plasma displays offer flicker-free images even at lower refresh rates because the color pixels retain their color until a color change occurs.
- In movie playback, a frame rate of 24 frames per second is used. This corresponds to the standard. However, there are projections that work with a frame rate that is twice as high, namely 48 frames per second. This technology is called High Frame Rate( HFR) and is characterized by a more detailed reproduction of scenes with fast movements; in addition, flickering is no longer perceptible.