120 Hz

(redirected from 72Hz)

120 Hz

The frame rate of many modern flat panel TVs, which is designed to improve fast action and movies by providing smoother transitions from frame to frame. The TV doubles the common digital frame rate of 60 frames per second (fps) to 120 fps by duplicating each frame and displaying them all in one second. However, the duplicated frames are altered (interpolated) to become transition frames between the original frames and the following ones (see below).

Another advantage to 120 Hz is that it improves the conversion of movies shot at 24 fps to TVs that run at 60 fps (60 Hz). In order to fit 24 movie frames into 60 TV frames, the traditional telecine method generates uneven transitions because 24 does not divide evenly into 60. Telecine converts one frame into three frames and the next frame into two frames, called "3:2 pulldown." However, since 24 divides evenly into 120, every movie frame can be interpolated into five video frames, known as "5:5 pulldown." In addition, HDTVs have also been made with 48, 72 and 96 Hz frame rates because 24 divides evenly into these numbers. See 240 Hz, 480 Hz and telecine.


Duplicate and Smooth
By doubling the frame rate, a transition frame can be created between each two original frames.







5:5 Pulldown
Since 24 divides evenly into 120, each film frame shot at 24 fps can be converted into the same number of video frames. See telecine.
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