3 ms·

I’m very suspicious of this 75Hz number. We’ve also heard that 60Hz is the limit of human perception but I think we all know now that we actually perceive highe

I’m very suspicious of this 75Hz number. We’ve also heard that 60Hz is the limit of human perception but I think we all know now that we actually perceive higher than that (seeing flicker at 120Hz, blind A/B testing of 240Hz monitors, even perceptual flickering for some people in 1000Hz PWM LEDs). Even if that 75Hz number were derived from deep understanding and measurement of the entire visual pathway, there are variations in perception for people, there most likely are for dogs as well.

waiquoo 7y ago
60Hz is the 'flicker fusion rate', meaning if you were changing the frequency of a flashing, stationary LED, ~60Hz would be the frequency where perception transitions from visibly flickering to apparently continuous. It's a lower threshold for refresh rate in the human eye. When you have complex refreshing images (a 2d computer screen rather than a point-like LED, diverse motion, depth, etc), you are likely to notice flickering (or tearing, jittering, non-smooth motion) if the refresh rate is near this minimum.
- barrkel 7y ago
  People routinely watch movies which refresh at 24Hz and motion is apparently continuous. Perceiving flicker has a higher threshold. I can perceive 60Hz flicker in my peripheral vision easily enough. Other sources online (you can find lots of them but I didn't see an obvious authoritative article) suggest that 16Hz is the flicker fusion rate for motion in humans. Flicker fusion for continuous brightness (CFF) is somewhere around 30Hz per https://www.nature.com/articles/s41598-017-15034-z https://www.nature.com/articles/s41598-017-15034-z and it rises with brightness - this paper is about testing how it changes in different circumstances.
  - svachalek 7y ago
    Unless the camera moves fast and then it looks like a slideshow. Whenever they pan across a landscape it makes me grit my teeth.
    - mdpye 7y ago
      This is often exacerbated horribly by the fact that the 50 or 60 FPS output doesn't divide well by the 24 FPS source material. It was smoother in the cinema, when it was projected at 24 FPS...
      - joshspankit 7y ago
        Fair point, but I (and many others) see stutter in theatre as well. Most of the reason you don’t is because filmmakers know very well what their “maximum pan speed” is and they stay as far away from it as possible.
Someone 7y ago
The limit depends on the size of the source, contrast, location on the eye of the source (rods are much ‘faster’ than cones, so we see flicker better out of the corners of our eyes), and probably a few other factors. 1000Hz I find hard to fathom, though. Would want to see what these signals look like.
deleted 7y ago
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ColanR 7y ago
And don't forget about harmonics. Seems like flicker at higher refresh rates would happen whenever the mental and external rates synchronize.

waiquoo 7y ago

60Hz is the 'flicker fusion rate', meaning if you were changing the frequency of a flashing, stationary LED, ~60Hz would be the frequency where perception transitions from visibly flickering to apparently continuous. It's a lower threshold for refresh rate in the human eye. When you have complex refreshing images (a 2d computer screen rather than a point-like LED, diverse motion, depth, etc), you are likely to notice flickering (or tearing, jittering, non-smooth motion) if the refresh rate is near this minimum.

barrkel 7y ago
People routinely watch movies which refresh at 24Hz and motion is apparently continuous. Perceiving flicker has a higher threshold. I can perceive 60Hz flicker in my peripheral vision easily enough. Other sources online (you can find lots of them but I didn't see an obvious authoritative article) suggest that 16Hz is the flicker fusion rate for motion in humans. Flicker fusion for continuous brightness (CFF) is somewhere around 30Hz per https://www.nature.com/articles/s41598-017-15034-z https://www.nature.com/articles/s41598-017-15034-z and it rises with brightness - this paper is about testing how it changes in different circumstances.
- svachalek 7y ago
  Unless the camera moves fast and then it looks like a slideshow. Whenever they pan across a landscape it makes me grit my teeth.
  - mdpye 7y ago
    This is often exacerbated horribly by the fact that the 50 or 60 FPS output doesn't divide well by the 24 FPS source material. It was smoother in the cinema, when it was projected at 24 FPS...
    - joshspankit 7y ago
      Fair point, but I (and many others) see stutter in theatre as well. Most of the reason you don’t is because filmmakers know very well what their “maximum pan speed” is and they stay as far away from it as possible.

Someone 7y ago

The limit depends on the size of the source, contrast, location on the eye of the source (rods are much ‘faster’ than cones, so we see flicker better out of the corners of our eyes), and probably a few other factors. 1000Hz I find hard to fathom, though. Would want to see what these signals look like.

deleted 7y ago

[deleted]

ColanR 7y ago

And don't forget about harmonics. Seems like flicker at higher refresh rates would happen whenever the mental and external rates synchronize.