Human Eye's Oscillation Rate Determines Smooth Frame Rate

jones_supa writes: It should be safe to conclude that humans can see frame rates greater than 24 fps. The next question is: why do movies at 48 fps look "video-y," and why do movies at 24 fps look "dreamy" and "cinematic." Why are games more realistic at 60 fps than 30 fps? Simon Cooke from Microsoft (Xbox) Advanced Technology Group has an interesting theory to explain this all. Your eyes oscillate a tiny amount, ranging from 70 to 103 Hz (on average 83.68 Hz). So here's the hypothesis: The ocular microtremors wiggle the retina, allowing it to sample at approximately 2x the resolution of the sensors. Showing someone pictures that vary at less than half the rate of the oscillation means we're no longer receiving a signal that changes fast enough to allow the supersampling operation to happen. So we're throwing away a lot of perceived-motion data, and a lot of detail as well. Some of the detail can be restored with temporal antialiasing and simulating real noise, but ideally Cooke suggests going with a high enough frame rate (over 43 fps) and if possible, a high resolution.

Comments

Re:"Your eyes oscillate"??

[tlhIngan]

The whole eye. Our eyes actually cannot detect a static edge, only transitions. The reason we can see non-moving objects is that the oscillations of the eye provide the transitions. There's a simple experiment from long ago which illustrates this vividly: put a black square on a white background, track a subject's eye motion and move that target with the eye motion so that the image is always hitting the retina at the same location, and voila, the subject cannot see that target.

The other reason is the "sensors" we have are quite poor - the eyeball itself is actually a very low resolution device - the high resolution center part of the eye covers such a narrow field of view that it's practically useless if it was a fixed camera, while the peripheral vision is so low res it's unusable.

Instead, what happens is we evolved a gigantic amount of wetware to process the image into a high-resolution image we perceive - the brain does a lot of visual processing, and the eyes rapidly move (or oscillate) to move the sharp high-res center vision around to give you a much higher "virtual resolution" than the actual Mk. 1 Eyeball can achieve.

Of course, this visual processing comes at a price - optical illusions abound because it's very easy to trick the wetware into seeing things that aren't there, because the information is often interpolated, shifted in time, etc.

Re:Get rid of Frames!!!!

[Megane]

That's like saying laserdisc is digital "because it's got pits and non-pits". Except that the length of the pits and non-pits is very much analog. (It's a full-bandwidth FM signal driven to maximum overmodulation. VHS does a similar thing.) In other words, the digital-ness becomes analog if you look even closer.