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To minimize the perceived flicker, projectors employed dual- and triple-blade shutters, so each frame was displayed two or three times, increasing the flicker rate to 48 or 72 hertz and reducing eye strain. Thomas Edison said that 46 frames per second was the minimum needed for the eye to perceive motion: "Anything less will strain the eye."
While 120 fps looks "realistic", the stroboscopic look can still be seen, which also happens on 60 Hz monitors playing 60 fps video and sometimes excessive motion blur, depending on the camera and shutter speed that was used when the video was recorded. Otherwise, videos over 200 fps are more preferred, since they look more fluid and realistic ...
For the purposes of presenting moving images, the human flicker fusion threshold is usually taken between 60 and 90 Hz, though in certain cases it can be higher by an order of magnitude. [5] In practice, movies since the silent era are recorded at 24 frames per second and displayed by interrupting each frame two or three times for a flicker of ...
The human eye is most sensitive to flicker at the edges of the human field of view (peripheral vision) and least sensitive at the center of gaze (the area being focused on). As a result, the greater the portion of our field of view that is occupied by a display, the greater is the need for high refresh rates.
In the case of filmed material, as 120 is an even multiple of 24, it is possible to present a 24 fps sequence without judder on a well-designed 120 Hz display (i.e., so-called 5-5 pulldown). If the 120 Hz rate is produced by frame-doubling a 60 fps 3:2 pulldown signal, the uneven motion could still be visible (i.e., so-called 6-4 pulldown).
A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...
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The human eye can perceive scenes with a very high dynamic contrast ratio, around 1,000,000:1. Adaptation is achieved in part through adjustments of the iris and slow chemical changes, which take some time (e.g. the delay in being able to see when switching from bright lighting to pitch darkness). At any given time, the eye's static range is ...