According to the query of Aiwen Education Network, a photo is a single image of the smallest unit in image animation. One frame is a still picture, and successive frames form an animation, such as a TV image. Quantifier, amplitude, used in calligraphy and painting. A picture, photograph, etc.

In the process of showing the film, the pictures are displayed on the screen one by one. When the picture frame moved away, the light was blocked and there was a brief darkness on the screen. After each frame is displayed, the screen will be dimmed. However, this extremely short darkness is made up by the phenomenon of "visual persistence" in visual physiology when human eyes observe the scenery. It takes a short time for light signals to enter the brain nerves, and when the light effect ends, the vision does not disappear immediately. This visual phenomenon is called "visual persistence".