4 ms·

An alternative to infinite refresh rate is to show each frame only a fraction of the normal frame time, i.e. to quickly "flash" the individual frames and showin

An alternative to infinite refresh rate is to show each frame only a fraction of the normal frame time, i.e. to quickly "flash" the individual frames and showing a black screen otherwise. This reduces the maximum screen brightness, an it requires a minimum frame rate to avoid flicker, but it reduces the type of "eye tracking blur" (persistence blur) which isn't present in real life. To be precise, to completely remove the tracking blur you would need to flash each frame only for an infinitesimal time period, which of course isn't realistic. But VR headsets do use this flashing/strobing approach. By the way, this is also the reason why CRT and Plasma screens had much better motion clarity than LCD or OLED. The former flash each frame for a short time, while the latter "sample and hold" the frame for the entire frame time (e.g. 1/60th of a second for 60 Hz). 60 FPS on a CRT looks probably more fluid than 120 FPS on an OLED. Another option for games is to indeed add a lot of frames by using reprojection techniques. This can approximate the real camera movements without needing to render a ton of expensive frames in the engine. This also is already used in VR, just currently not at overly high frame rates. This great article goes into more detail: https://blurbusters.com/frame-generation-essentials-interpolation-extrapolation-and-reprojection/ https://blurbusters.com/frame-generation-essentials-interpol... Something like 1000 FPS with reprojection are apparently quite realistic, which should solve the problem of tracking blur without reducing screen brightness.

account42 3y ago
> Something like 1000 FPS with reprojection are apparently quite realistic, which should solve the problem of tracking blur without reducing screen brightness. Is a 1000 FPS screen more realistic than a screen capable of the higher maximum brightness needed to compensate for black frame insertion though? HDR screens are already a thing and you could already gain persistence improvements there for LDR scenes without needing any new hardware by always driving pixels at max brighness but only for a reduced time depending on the target luminance. Or just reduce the ambient light enough - I even run even my LDR monitor at 10% brightness.
- cubefox 3y ago
  As far as I understand, the only thing that matters for reducing unrealistic "tracking blur" is indeed how short a frame is displayed on screen. Which could be achieved by strobing / black frame insertion or by increasing frame rate. Or even both, as in some VR applications. So the effect should be the same, except for the brightness thing, which may not be a problem if there is a lot of screen brightness headroom anyway. For HDR LCD TVs the LED backlights get quite bright actually. OLED not so much. One advantage of higher frame rates (as opposed to strobing) would be quicker input responses to, e.g., moving the camera. That's not overly important on a normal screen but quite significant on a VR headset where we expect head movements to be represented very quickly.
- mrob 3y ago
  Low persistence only gives perfect motion when your eye motion perfectly matches the object motion[0]. For all other motion, low persistence causes false images to be generated on the retina, which can be seen as "phantom array effect"[1]. I think interpolation up to several kilohertz is the best solution, preferable starting from a moderately high frame rate (e.g. 200fps) to minimize the latency penalty and artifacts. [0] https://en.wikipedia.org/wiki/Smooth_pursuit https://en.wikipedia.org/wiki/Smooth_pursuit [1] https://en.wikipedia.org/wiki/Flicker_fusion_threshold#Visual_phenomena https://en.wikipedia.org/wiki/Flicker_fusion_threshold#Visua...
  - cubefox 3y ago
    I think the second effect is quite small compared to the first because CRTs are generally good at the first but don't suffer much from the second, as far as I'm aware.
    - mrob 3y ago
      CRTs suffer strongly from phantom array effect, but individual sensitivity to this effect varies. The people who notice it are the same ones who complain about PWM lighting.
      - cubefox 3y ago
        I think most people don't see this effect on CRTs, so I wouldn't say they (the CRTs) suffer much from it.
terribleperson 3y ago
Many gaming monitors offer a 'blur reduction' feature using a strobing backlight.

account42 3y ago

> Something like 1000 FPS with reprojection are apparently quite realistic, which should solve the problem of tracking blur without reducing screen brightness. Is a 1000 FPS screen more realistic than a screen capable of the higher maximum brightness needed to compensate for black frame insertion though? HDR screens are already a thing and you could already gain persistence improvements there for LDR scenes without needing any new hardware by always driving pixels at max brighness but only for a reduced time depending on the target luminance. Or just reduce the ambient light enough - I even run even my LDR monitor at 10% brightness.

cubefox 3y ago
As far as I understand, the only thing that matters for reducing unrealistic "tracking blur" is indeed how short a frame is displayed on screen. Which could be achieved by strobing / black frame insertion or by increasing frame rate. Or even both, as in some VR applications. So the effect should be the same, except for the brightness thing, which may not be a problem if there is a lot of screen brightness headroom anyway. For HDR LCD TVs the LED backlights get quite bright actually. OLED not so much. One advantage of higher frame rates (as opposed to strobing) would be quicker input responses to, e.g., moving the camera. That's not overly important on a normal screen but quite significant on a VR headset where we expect head movements to be represented very quickly.
mrob 3y ago
Low persistence only gives perfect motion when your eye motion perfectly matches the object motion[0]. For all other motion, low persistence causes false images to be generated on the retina, which can be seen as "phantom array effect"[1]. I think interpolation up to several kilohertz is the best solution, preferable starting from a moderately high frame rate (e.g. 200fps) to minimize the latency penalty and artifacts. [0] https://en.wikipedia.org/wiki/Smooth_pursuit https://en.wikipedia.org/wiki/Smooth_pursuit [1] https://en.wikipedia.org/wiki/Flicker_fusion_threshold#Visual_phenomena https://en.wikipedia.org/wiki/Flicker_fusion_threshold#Visua...
- cubefox 3y ago
  I think the second effect is quite small compared to the first because CRTs are generally good at the first but don't suffer much from the second, as far as I'm aware.
  - mrob 3y ago
    CRTs suffer strongly from phantom array effect, but individual sensitivity to this effect varies. The people who notice it are the same ones who complain about PWM lighting.
    - cubefox 3y ago
      I think most people don't see this effect on CRTs, so I wouldn't say they (the CRTs) suffer much from it.

terribleperson 3y ago

Many gaming monitors offer a 'blur reduction' feature using a strobing backlight.