How many frames per second can we actually see?
Frame rate is the rate at which images appear on a screen.Film and video cameras, computer graphics, and motion capture systems are all covered by the term.The frame rate can be expressed inhertz.
The temporal sensitivity and resolution of human vision varies depending on the type and characteristics of visual stimuli.The human visual system can process 10 to 12 images per second.Modulated light is seen as stable by the majority of participants in studies when the rate is higher.The flicker fusion threshold is a perception of light as steady.The flicker fusion threshold can be much higher in the hundreds of hertz when the light is non-uniform.People have been found to recognize a specific image in a series of different images, each of which lasts as little as 13 milliseconds.Persistence of vision can account for a very short single-millisecond visual stimuli having a perceived duration of between 100 and 400 ms.A 10 ms green flash of light is perceived as a single yellow flash by some people.[5]
The early silent films had a frame rate of 16 to 24 frames per second, but since the cameras were hand-cranked, the rate often changed during the scene to fit the mood.The frame rate in the theater could be changed by adjusting the rheostat.Film companies often wanted theaters to show their silent films at higher frame rates than they were filmed at.The frame rates were enough for the sense of motion, but it was not appreciated.To reduce the perceived flicker, projectors used dual- and triple-blade shutters, so each frame was displayed two or three times, increasing the flicker rate to 48 or 72 hertz.The minimum needed for the eye to see motion is 46 frames per second.In the late 1920s, the frame rate for silent films increased to between 20 and 26 frames per second.[8]
Variations in film speed were not allowed because the human ear is more sensitive than the eye to changes in frequencies.The industry chose 24 frames per second for sound films as a compromise because many theaters had shown silent films at 22 to 26.The standard rate for 35mm sound film was 24 frames per second from 1927 to 1930.The film travels through the projector at a rate of 456 millimetres per second.This allowed simple two-blade shutters to give a projected series of images at 48 per second.The 35mm film projector uses three-blade shutters to give 72 images per second.[8]
In drawn animation, moving characters are often shot on twos, that is to say, one drawing is shown for every two frames of film, meaning there are only 12 drawings per second.The fluidity is satisfactory for most subjects even though the image update rate is low.When a character is required to perform a quick movement, it is usually necessary to return to "on ones", as "twos" are too slow to convey the motion adequately.The eye is fooled by a blend of the two techniques.[13]
The animation was usually shot on threes or fours and was produced as cheaply as possible.There are three or four frames per drawing.This equates to 8 or 6 drawings per second.It is drawn on threes.It was 13 and 14.
Due to the mains frequencies of electric grids, analog television broadcast was developed with frame rates of 50 and 60 frames per second.The stability of the electricity grid made it logical to use it for synchronization.