5 ms·

And 120hz refresh rates... almost 20 years ago!

by 3fe9a03ccd14ca5 7y ago

hunter2_ 7y ago
I never noticed a benefit over 70 or so. The flicker of 60 made my eyes bleed though. Then with LCDs 60 was fine.
- aasasd 7y ago
  I still don't know what it is about 60 Hz that made me see the flicker plainly as a strobing light. TVs at 50 Hz—nothing (other than being generally bleh back then). Had to use 800x600 instead of 1024x768 just to have 85 Hz instead. On LCDs, I still can see faint flicker on some static backgrounds, and I think 60 Hz might play a role here too—though it seems to also depend on the brightness and Flux being on or off. E.g. on https://marctenbosch.com/news/ https://marctenbosch.com/news/
  - extrapickles 7y ago
    The LCDs you see this on are 6-bit color displays using temporal dithering to pretend to be 8-bit color.
    - exikyut 7y ago
      That's why drop shadows look horrible when I'm looking at my screen at the wrong angle... I knew it was a dithering thing, forgot LCDs were 6-bit.
      - blattimwind 7y ago
        Only cheap/low-end LCDs are 6 bit. Most are 8 bit with no dithering.
    - aasasd 6y ago
      Should this be the case with a Macbook, even if a sorta old one? Because that's the machine I've seen the flicker on, for the past bunch of years.
    - garaetjjte 6y ago
      The reason for flickering on specific patterns is independent of temporal dithering. This is caused by cyclic polarity inversion: http://www.lagom.nl/lcd-test/inversion.php http://www.lagom.nl/lcd-test/inversion.php (temporal dithering usually is visible as slight noise on darker shades)
  - TylerE 7y ago
    AC power is 60hz so room lighting (especially florescent) also flickers at 60hz. It’s a sort of wagon wheel effect.
    - aasasd 7y ago
      I dropped a hint right there that the AC frequency is definitely not 60 Hz where I am.
      - TylerE 6y ago
        Actually you didn't. There were many countries that used PAL for TV broadcasts but have 60hz AC.
        aasasd 6y ago
        Hmm, afaik the framerates were chosen to be equal to the AC freq so that there are no glitches in the image. Do those countries have converters or something in the TVs, or did they watch jumpy image?
        hunter2_ 6y ago
        They didn't say PAL, they said "50 Hz TV." PAL and 50 Hz TV are not synonymous. Brazil has 60 Hz AC and uses PAL-M which is 60 Hz TV. AC=TV even in these odd cases. Old CRTs couldn't possibly clock their flyback to anything but mains.
    - hunter2_ 6y ago
      Fluorescent lighting, assuming it's not starting to fail, flickers at 120 Hz because each half cycle lights it up equally (+ or - doesn't matter). Incandescent also has 120 Hz flicker but the valleys are almost as bright as the peaks (slow response) so it's essentially imperceptible. Cheap LEDs like some holiday minilights are rectified so they'll flicker at 60 Hz and I can't stand them.
  - blattimwind 7y ago
    Three reasons: You sit much closer to a computer screen compared to a TV, so your peripheral vision has a better chance with the computer screen to see flicker. Computer CRTs supported higher refresh rates, so they used phosphors with shorter afterglow (otherwise you'd get ghosting/S&H-like artifacts like TFTs produce). You can notice this one when you photograph a computer CRT vs. photographing a TV with the same shutter speed. And at the end of CRT TVs a lot of them were 100 Hz.
    - aasasd 6y ago
      Interesting hypotheses, though I still can't quite accept them as final. I seem to recall that the effect was much more noticeable, not only when sitting in front of the screen—basically enter the room and there it is. And I think that I've experimented with lower refresh rates too, at least I definitely had the time and inclination—but can't remember if the monitor allowed them with the available resolutions. It's stuck in my memory that only 60 Hz does this. When I get rich and have lots of free time, I'll probably buy a bunch of old CRTs just to dig to the roots of this.
    - aasasd 6y ago
      Btw, I count only two reasons there.
      - blattimwind 6y ago
        (1) You sit much closer ... (2) Computer CRTs supported ... (3) And at the end ...
foobarbecue 7y ago
Yeah, and I had 3d shutter glasses that worked great with the trinitron... In 2000 or so. Nvidia 3d Vision came along later but now sadly those product lines are abandoned, I guess due to VR which is just not what I want at all
- ccozan 7y ago
  Wow, such memories with the 3D Vision. Was quite visionary. And indeed I had to buy a Sony Trinitron with 120Hz refresh otherwise it wouldn't work. I remember playing MoH:AA, the play experience was quite out of this world.
  - foobarbecue 6y ago
    Coincidentally, my whole team still uses Nvidia 3d Vision 2 at work, despite lack of support from Nvidia. One of the reasons I took the job is because I saw they were using it. Not having access to those systems is one of the hardships of working at home. https://www.jpl.nasa.gov/news/news.php?feature=7638&fbclid=IwAR1GqqPKs-PrKJdOWzc5kU8I900arHiJwJyQrh_vywuOD6XrtzLP1W8Eois https://www.jpl.nasa.gov/news/news.php?feature=7638&fbclid=I...

And 120hz refresh rates... almost 20 years ago!

hunter2_ 7y ago

I never noticed a benefit over 70 or so. The flicker of 60 made my eyes bleed though. Then with LCDs 60 was fine.

aasasd 7y ago
I still don't know what it is about 60 Hz that made me see the flicker plainly as a strobing light. TVs at 50 Hz—nothing (other than being generally bleh back then). Had to use 800x600 instead of 1024x768 just to have 85 Hz instead. On LCDs, I still can see faint flicker on some static backgrounds, and I think 60 Hz might play a role here too—though it seems to also depend on the brightness and Flux being on or off. E.g. on https://marctenbosch.com/news/ https://marctenbosch.com/news/
- extrapickles 7y ago
  The LCDs you see this on are 6-bit color displays using temporal dithering to pretend to be 8-bit color.
  - exikyut 7y ago
    That's why drop shadows look horrible when I'm looking at my screen at the wrong angle... I knew it was a dithering thing, forgot LCDs were 6-bit.
    - blattimwind 7y ago
      Only cheap/low-end LCDs are 6 bit. Most are 8 bit with no dithering.
  - aasasd 6y ago
    Should this be the case with a Macbook, even if a sorta old one? Because that's the machine I've seen the flicker on, for the past bunch of years.
  - garaetjjte 6y ago
    The reason for flickering on specific patterns is independent of temporal dithering. This is caused by cyclic polarity inversion: http://www.lagom.nl/lcd-test/inversion.php http://www.lagom.nl/lcd-test/inversion.php (temporal dithering usually is visible as slight noise on darker shades)
- TylerE 7y ago
  AC power is 60hz so room lighting (especially florescent) also flickers at 60hz. It’s a sort of wagon wheel effect.
  - aasasd 7y ago
    I dropped a hint right there that the AC frequency is definitely not 60 Hz where I am.
    - TylerE 6y ago
      Actually you didn't. There were many countries that used PAL for TV broadcasts but have 60hz AC.
      - aasasd 6y ago
        Hmm, afaik the framerates were chosen to be equal to the AC freq so that there are no glitches in the image. Do those countries have converters or something in the TVs, or did they watch jumpy image?
      - hunter2_ 6y ago
        They didn't say PAL, they said "50 Hz TV." PAL and 50 Hz TV are not synonymous. Brazil has 60 Hz AC and uses PAL-M which is 60 Hz TV. AC=TV even in these odd cases. Old CRTs couldn't possibly clock their flyback to anything but mains.
  - hunter2_ 6y ago
    Fluorescent lighting, assuming it's not starting to fail, flickers at 120 Hz because each half cycle lights it up equally (+ or - doesn't matter). Incandescent also has 120 Hz flicker but the valleys are almost as bright as the peaks (slow response) so it's essentially imperceptible. Cheap LEDs like some holiday minilights are rectified so they'll flicker at 60 Hz and I can't stand them.
- blattimwind 7y ago
  Three reasons: You sit much closer to a computer screen compared to a TV, so your peripheral vision has a better chance with the computer screen to see flicker. Computer CRTs supported higher refresh rates, so they used phosphors with shorter afterglow (otherwise you'd get ghosting/S&H-like artifacts like TFTs produce). You can notice this one when you photograph a computer CRT vs. photographing a TV with the same shutter speed. And at the end of CRT TVs a lot of them were 100 Hz.
  - aasasd 6y ago
    Interesting hypotheses, though I still can't quite accept them as final. I seem to recall that the effect was much more noticeable, not only when sitting in front of the screen—basically enter the room and there it is. And I think that I've experimented with lower refresh rates too, at least I definitely had the time and inclination—but can't remember if the monitor allowed them with the available resolutions. It's stuck in my memory that only 60 Hz does this. When I get rich and have lots of free time, I'll probably buy a bunch of old CRTs just to dig to the roots of this.
  - aasasd 6y ago
    Btw, I count only two reasons there.
    - blattimwind 6y ago
      (1) You sit much closer ... (2) Computer CRTs supported ... (3) And at the end ...

foobarbecue 7y ago

Yeah, and I had 3d shutter glasses that worked great with the trinitron... In 2000 or so. Nvidia 3d Vision came along later but now sadly those product lines are abandoned, I guess due to VR which is just not what I want at all

ccozan 7y ago
Wow, such memories with the 3D Vision. Was quite visionary. And indeed I had to buy a Sony Trinitron with 120Hz refresh otherwise it wouldn't work. I remember playing MoH:AA, the play experience was quite out of this world.
- foobarbecue 6y ago
  Coincidentally, my whole team still uses Nvidia 3d Vision 2 at work, despite lack of support from Nvidia. One of the reasons I took the job is because I saw they were using it. Not having access to those systems is one of the hardships of working at home. https://www.jpl.nasa.gov/news/news.php?feature=7638&fbclid=IwAR1GqqPKs-PrKJdOWzc5kU8I900arHiJwJyQrh_vywuOD6XrtzLP1W8Eois https://www.jpl.nasa.gov/news/news.php?feature=7638&fbclid=I...