What is the Frame Rate?

The frame rate is the number of images or frames that a device displays or records per second. It is measured in frames per second (fps).

What is the Frame Rate used for?

The number of frames per second plays an essential role in the representation and perception of motion in videos, movies, animations and video games. The frame rate determines how many frames or images are displayed or recorded per second. This rate has several purposes and effects on the user’s visual experience:

• Motion perception: For the human eye to perceive a set of still images as continuous motion, a certain frame rate is required. Below a certain limit, we perceive motion as “choppy” or “jumpy”.
• Visual fluency: A higher frame rate generally results in smoother playback. For example, a video at 60 fps will look smoother than one at 24 fps. This is especially noticeable in fast-moving scenes.
• Style and aesthetics: In some contexts, a specific frame rate may be chosen for stylistic reasons. For example, many movies use 24 fps because this rate has historically been associated with the cinematic “look”.
• Performance and capability: In video games, the frame rate can indicate how well the hardware is performing. If a game falls below a certain rate, it can be a sign that the computer or console is struggling to process information quickly.
• Interaction and responsiveness: In interactive environments, such as video games or virtual reality applications, a high frame rate is crucial not only for visual perception but also for user response and interaction. A higher frame rate can lead to a more responsive experience.
• Virtual Reality Comfort: In virtual reality platforms, maintaining a high frame rate is essential to prevent motion sickness and provide a comfortable user experience.

Frame Rate in Different Environments

As we have just discussed, the frame rate affects the user experience, but not all devices need to offer the same number of frames per second. Here is the most common FPS number in different industries:

• Cinema: Traditionally, movies are recorded at 24 fps. This rate has long been the standard because it is considered to provide a natural motion look while preserving the amount of film used.
• Television: Depending on the country and television standard, common rates are 25 fps (PAL, used mainly in Europe) or 30 fps (NTSC, used mainly in North America).
• Video games: In this area, a higher frame rate is often desirable because it can make the action feel more fluid. It is common for games to aim for 60 fps or even higher, although the ability of a console or PC to achieve this will depend on its hardware and the graphical demands of the particular game.
• Virtual Reality: For VR, high frame rates are crucial. A low rate can make users feel dizzy or disoriented. Generally, look for at least 90 fps for a comfortable experience.
• High-speed cameras: These are specialized cameras that can record at extremely high frame rates, often in the thousands or even tens of thousands of fps. They are primarily used to capture very fast events, such as explosions or scientific experiments, and then play them back in slow motion.

What is the limit of Frames Per Second that the Human Eye can perceive?

Determining an exact limit of fps (frames per second) that the human eye can perceive is complex and subject to debate because visual perception is not based solely on “frames” as digital devices do. Some aspects must be taken into account.

• It is considered that the human eye needs at least 16 to 24 fps to perceive a series of images as continuous motion. Below that range, motion begins to look choppy.
• As the frame rate increases, the perception of motion becomes more fluid. Most people can tell the difference between, for example, 30 fps and 60 fps, especially in scenarios with a lot of motion, such as in video games or sports.
• Above 60, the human eye’s ability to distinguish improvements in fluidity is reduced. That is, while there may technically be a difference between 120 fps and 240 fps, most people would have difficulty noticing it under normal conditions.
• The ability to discern differences in frame rate can vary from person to person. Some individuals, especially those accustomed to certain types of content (such as professional video game players), may be more sensitive to differences in frame rates.
• Perception can also be affected by the type of content, motion in the scene, screen quality, monitor refresh rate and other technical factors.