Eye refresh rate

[apendrapew]

I was wondering what your answers would be to this.

If the eye can only register 24 images per second, how is it that I can tell the difference in video rendering between say, 30 fps and 60? Is it because images and motion are processed separately? Frankly, I don't see how that would matter. Anyway, the eye gets the 24 images per second loaded into iconic memory. Somehow, though, it gets other data that lets it know it's getting more than that. What kind of data is it?

[Watcher]

Perception is an interesting topic... I did find a little information out there. One of the phenomena that adds to your ability to detect the difference in those frames rates is "persistence of vision" or the fact that an image is retained for a split second after exposure on the retina.

http://www.fact-index.com/p/pe/persi..._vision_1.html

The other factor is something called "flicker fusion threshold" which is directly related to the detection of flicker, but is a function of the lighting and viewing conditions and I would guess a lot of other factors. So it would seem to me that there is no "hard" limit for the minimum frame rate where flicker is detected.

http://www.fact-index.com/f/fl/flick...threshold.html

[SkippingStones]

Sort of off topic but a cool way to test your monitor's refresh rate is bring up a bright screen then turn all other lights off so it's just the monitor that's lighting the room. Then take a pencil or pen and spin it fast on a smooth surface in front of the monitor. It looks like the blades of a ceiling fan. I counted about twice as many "blades" at 85 Hz as at 60 Hz.

[hotsexyangelprincess]

whoa. someone once told me that the eye perceived things at 60 times a second, and that TV and fluorescent lights run at the same rate.

[Persol]

Below that some people tend to see a slide show... not motion. About 60hz our braisn pretty reliably fool us into thinking it is motion.

[invert_nexus]

It has to do with the way the image is presented, right? 24 frames per second is good for films because it is a light that is going through the film and reflecting from a wall. But on a computer monitor it would flicker like crazy.

Ntsc televisions operating at 60 hz is somewhat misleading as it is interlaced. First the upper field is shown then the lower. (by field, not upper half and lower half. Interlaced like a comb.) So the actual image is coming at us at 30 frames per second (actually 29.997 I believe). And then there is the property of the phospors to linger on the screen. Without that we would see the comb effect. Not entirely sure of the frequency of progressive scan televisions.

[Persol]

Without that we would see the comb effect

Do you mean the same effect you get whwen you use interlaced monitors?

[invert_nexus]

Do you mean the same effect you get whwen you use interlaced monitors?

You mean the effect you get when viewing interlaced video on a monitor? I've never seen an interlaced monitor, myself. Is there such a thing?

[apendrapew]

Yeah man, TVs are interlaced.

[invert_nexus]

Yeah, I suppose you can call a tv a monitor. But, you don't see interlaced "comb" effects on a tv. Because the phosphors glow and the blurring effect. So, Persol must have been speaking of something else other than a tv.

[Persol]

Way back in the day I had an interlaced monitor. Above a certain resolution you'd get what appeared to be the same combing effect you got with interlaced mode.

http://www.pccomputernotes.com/monitors/monitors1.htm

If the scanning beam hits each and every line of pixels, in succession, on each pass, then the monitor is known as a non-interlaced monitor. A non-interlaced monitor is preferred over an interlaced monitor. The electron beam on an interlaced monitor scans the odd numbered lines on one pass, then scans the even lines on the second pass. This results in an almost imperceivable flicker that can cause eye-strain.