Perception of Film

A persistent image from Sony Pictures 2008 motion-picture
Nick and Nora's Infinite Playlist.

With respect to the perception of realism when viewing motion pictures, persistent images prevent us from seeing that motion-picture screens are dark when the projector moves from one frame to the next. Persistent images last an average of approximately one quarter second after the stimulus has been removed. Perception occurs with short exposure time because the persistent image keeps the image available to the viewer slightly longer than the actual presentation time.

Persistent images are crucial to the perception of realistic motion-picture and television pictures. When motion picture films are projected, it is mandatory to darken the screen with a rotating shutter when the film is being moved from one frame to the next. In other words, the persistent image prevents the viewer from seeing the dark intervals which would appear as a flicker in the theater.

Earlier motion-pictures were nicknamed flicks because of they were made with 16 frames per second and the flicker was obvious to the naked eye. Because images are constructed sequentially with an electron beam, the persistent images are necessary for the viewers to see a complete picture. The duration of a persistent image may vary depending on several factors including the image's luminance level and whether the removal of stimulus is followed by another image or darkness.