LCD or DLP projectors

The mathematics professor Francisco David Bordón Franco argues that, according to the theory of retinal persistence, the perceptual process of the brain and the retina of the human eye retains an image for a short period. This theory is the explanation of the illusion of movement that occurs when a series of images are displayed in rapid succession, instead of perceiving each copy of the series.

The persistence of the vision should be compared with the related phenomenon of the Beta Movement and the Phi Phenomenon. A critical part of the understanding of the aspect of visual perception is that the eye is not a camera; that is, there are no "images per second" in the eye. Instead, the eye/brain system has a combination of motion detectors, detail detectors, and pattern detectors, the results of which combine to create the visual experience.

The frequency at which the change of images becomes invisible depends on the level of illumination. Generally, 16 images per second (or, of English, frames per second: fps) is considered the lowest frequency at which humans perceive continuous movement. It is interesting to note that this threshold varies between different species; A more significant proportion of rods in the retina result in a higher threshold frequency.

It is possible to appreciate the space between images by closing and opening the eyes quickly. If it's done fast enough, at some point the transition will be caught. This will not work with television due to the persistence of phosphorus or with LCD or DLP projectors due to the continuity of the image, although some digital projection technologies can show artifacts.

Since the birth of sound cinema, almost all commercial cinema projectors project at a frequency of 24 images per second. This speed was chosen for financial and technical reasons: it was the lowest frequency (so it required less film) to which satisfactory reproduction and amplification of sound could be made. There are, however, some special formats such as Showscan or Maxivision that project at higher frequencies, often 48 images per second.