What is meant by 'persistence of vision'? We are able to see the movie picturw 8n a cinema hall. How does this happen?
Answers
The ability of the human eye to continue to see the image of an object for a very short duration even after the removal of that object is called persistence of vision. Infact the sensation produced by the image of an object lasts for nearly 1/ 16th of a second on retina.
It is due to persistence of vision that we are able to see movie pictures in a cinema hall. The pictures in the form of a long film are projected on the screen at a rate of about 24 pictures per second. Under these conditions, the image of one picture persists on the retina of the eye till the image of the next picture falls on the screen, and so on. Due to this, the slightly different images of the successive pictures present on the film merge smoothly with one another and give us the feeling of continuity and moving images.
Persistence of vision works because the human eye and brain can only process 10 to 12 separate images per second, retaining an image for up to a fifteenth of a second. If a subsequent image replaces it in this period of time it will create the illusion of continuity.
The use of animation techniques to create moving images predates conventional cinema. Devices like the phenakistoscope (disk pictured above) and the zoetrope used the basic principles of animation to provide entertainment in the 19th century.
in today cenima a images flashes 12 sec for 1 so we feel image is moving
