Persistence-of-Vision
Persistence-of-Vision (POV) is a phenomenon where an image continues to be perceived by the human eye for a fraction of a second after its actual disappearance. This optical illusion has been fundamental in the development of several visual technologies, particularly in the fields of animation and cinema.
History
The concept of Persistence-of-Vision was first scientifically noted by the Austrian physicist Simon von Empis in 1640, although it was not until the 19th century that its implications for visual technology were fully explored. Here are some key milestones:
- 1824 - Peter Mark Roget published "Explanation of an Optical Deception in the Appearance of the Spokes of a Wheel Seen through Vertical Apertures," which discussed the phenomenon of persistence of vision, although he did not use that term.
- 1830s - The Phenakistoscope, one of the first animation devices, was invented independently by Joseph Plateau in Belgium and Simon von Stampfer in Austria. These devices used the principle of Persistence-of-Vision to create the illusion of movement from a series of still images.
- 1877 - Eadweard Muybridge used a series of still cameras to capture motion in phases, which when viewed in quick succession, utilized Persistence-of-Vision to show movement.
- 1894 - Thomas Edison introduced the Kinetoscope, a peep-show viewing device, which applied the principles of Persistence-of-Vision to deliver short films to individual viewers.
Scientific Explanation
The Persistence-of-Vision phenomenon occurs because:
- The human eye retains an image for approximately 1/16th to 1/50th of a second after the image has vanished.
- This brief retention, combined with the quick succession of images, tricks the brain into perceiving continuous motion.
Applications
Here are some notable applications of Persistence-of-Vision:
- Film and Television: Movies and TV shows are typically filmed and displayed at 24 frames per second (fps), which is sufficient to create the illusion of continuous motion due to Persistence-of-Vision.
- Animation: Traditional animation techniques involve drawing separate frames which are then rapidly shown to simulate movement.
- LED Displays: Modern digital displays often use POV to refresh images at high frequencies to create the appearance of continuous light emission.
Criticism and Misconceptions
While Persistence-of-Vision has been widely accepted as an explanation for how we perceive motion in films, some researchers argue:
- The phenomenon might not fully explain motion perception; instead, Phi Phenomenon or Beta Movement could play a larger role.
- Modern studies suggest that the perception of motion involves more complex cognitive processes beyond just the retention of an image.
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