Frame rate

"Update rate" redirects here. It is not to be confused with RAM update rate.
"Burst rate" redirects here. It is not to be confused with Burstable rate.

Frame rate, also known as frame frequency, is the frequency (rate) at which an imaging device displays consecutive images called frames. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate is usually expressed in frames per second (FPS).

Frame rate and human vision

Further information: Motion perception

The temporal sensitivity and resolution of human vision varies depending on the type and characteristics of visual stimulus, and it differs between individuals. The human visual system can theoretically process 1000 separate images per second but is not noticeable to the untrained eye after about 150 and up to around 240 where motion looks realistic.[1] Modulated light (such as a computer display) is perceived as stable by the majority of participants in studies when the rate is higher than 50 Hz through 90 Hz. This perception of modulated light as steady is known as the flicker fusion threshold. However, when the modulated light is non-uniform and contains an image, the flicker fusion threshold can be much higher.[2] With regard to image recognition, people have been found to recognize a specific image in an unbroken series of different images, each of which lasts as little as 13 milliseconds.[3] Persistence of vision sometimes accounts for very short single-millisecond visual stimulus having a perceived duration of between 100 ms and 400 ms. Multiple stimuli that are very short are sometimes perceived as a single stimulus, such as a 10 ms green flash of light immediately followed by a 10 ms red flash of light perceived as a single yellow flash of light.[4]


Silent films

Early silent films had stated frame rates anywhere from 16 to 24 frames per second (FPS),[5] but since the cameras were hand-cranked, the rate often changed during the scene to fit the mood. Projectionists could also change the frame rate in the theater by adjusting a rheostat controlling the voltage powering the film-carrying mechanism in the projector.[6] Silent films were often intended to be shown at higher frame rates than those used during filming.[7] These frame rates were enough for the sense of motion, but it was perceived as jerky motion. By using projectors with dual- and triple-blade shutters, the rate was multiplied two or three times as seen by the audience. Thomas Edison said that 46 frames per second was the minimum needed by the visual cortex: "Anything less will strain the eye."[8][9] In the mid to late 1920s, the frame rate for silent films increased to between 20 and 26 FPS.[8]

Sound films

When sound film was introduced in 1926, variations in film speed were no longer tolerated as the human ear is more sensitive to changes in audio frequency. Many theaters had shown silent films at 22 to 26 FPS which is why 24 FPS was chosen for sound. From 1927 to 1930, as various studios updated equipment, the rate of 24 FPS became standard for 35 mm sound film.[1] At 24 FPS the film travels through the projector at a rate of 456 millimetres (18.0 in) per second. This allowed for simple two-blade shutters to give a projected series of images at 48 per second, satisfying Edison's recommendation. Many modern 35 mm film projectors use three-blade shutters to give 72 images per second—each frame is flashed on screen three times.[8]

Digital video and television standards

There are three main frame rate standards in the TV and digital cinema business: 24p, 25p, and 30p. However, there are many variations on these as well as newer emerging standards. Frames per second are often expressed as hertz (1 Hz = 1 Fps).

See also


  1. 1 2 Read, Paul; Meyer, Mark-Paul; Gamma Group (2000). Restoration of motion picture film. Conservation and Museology. Butterworth-Heinemann. pp. 24–26. ISBN 0-7506-2793-X.
  2. James Davis (1986), Humans perceive flicker artefacts at 500 Hz, Wiley, PMC 4314649Freely accessible
  3. "Detecting meaning in RSVP at 13 ms per picture". SpringerLink. December 28, 2013.
  4. Robert Efron. "Conservation of temporal information by perceptual systems". Perception & Psychophysics. 14 (3): 518–530. doi:10.3758/bf03211193.
  5. Brown, Julie (2014). "Audio-visual Palimpsests: Resynchronizing Silent Films with 'Special' Music". In David Neumeyer. The Oxford Handbook of Film Music Studies. Oxford University Press. p. 588. ISBN 0195328493.
  6. Kerr, Walter (1975). Silent Clowns. Knopf. p. 36. ISBN 0394469070.
  7. Card, James (1994). Seductive cinema: the art of silent film. Knopf. p. 53. ISBN 0394572181.
  8. 1 2 3 4 Brownlow, Kevin (Summer 1980). "Silent Films: What Was the Right Speed?". Sight & Sound. 49 (3): 164–167. Archived from the original on 8 July 2011. Retrieved 2 May 2012.
  9. Thomas Elsaesser, Thomas Elsaesser; Barker, Adam (1990). Early cinema: space, frame, narrative. BFI Publishing. p. 284. ISBN 0-85170-244-9.
  10. "How many cels does a typical cartoon yield?"
  11. Todd-AO Specifications at a Glance, Widescreen Museum.
  12. Giardina, Carolyn (March 30, 2011). "James Cameron 'Fully Intends' to Make 'Avatar 2 and 3' at Higher Frame Rates". The Hollywood Reporter. Retrieved April 4, 2010.
  13. Jackson, Peter (12 April 2011). "48 Frames Per Second". Peter Jackson's Facebook page. Facebook. Retrieved 12 April 2011.
  14. Walters, Florence (25 April 2012). "The Hobbit previews to mixed reactions". The Daily Telegraph. London. Retrieved 30 April 2012.
  15. Gary Edgerton, The Columbia History of American Television, Columbia University Press, 2009, p. 51–52. ISBN 978-0-231-12165-1.
  16. Hoffmann, Hans; Takebumi Itagaki; David Wood; Alois Bock (December 2006). "Studies on the Bit Rate Requirements for a HDTV Format With 1920 × 1080 pixel Resolution, Progressive Scanning at 50 Hz Frame Rate Targeting Large Flat Panel Displays" (PDF). IEEE Transactions on Broadcasting. 52 (4): 420–434. doi:10.1109/tbc.2006.884735.
  17. "10 Things You Need to Know about 1080p50" (PDF). EBU Technical.
  18. Snell & Willcox
  19. List of 120Hz Monitors – Includes 144Hz, 240Hz
  20. Gaming Monitor List (120Hz, 144Hz, 160Hz, 165Hz, 180Hz, 200Hz, and 240Hz)
  21. High Frame-Rate Television, BBC White Paper WHP 169, September 2008, M Armstrong, D Flynn, M Hammond, S Jolly, R Salmon

External links

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