LightBoost

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NVIDIA 3D LightBoost™ is a technology introduced in 2011 as part of the NVIDIA 3D Vision 2 system. LightBoost is designed to improve the image presentation quality on LCDs when viewing 3D content with shutter glasses. However, LightBoost can also be of great advantage when viewing 2D content (without shutter glasses) as it helps to reduce motion blur.

Update (late 2016): Meanwhile, most of the current gamer monitors support some sort of strobed backlight for serving the same purpose as 2D LightBoost does. Different manufacturers use different names for basically the same thing, like MBR (Motion Blur Reduction, BenQ), ULMB (Ultra Low Motion Blur, part of 'G-Sync'), Motion240 (LG), etc.


Although LightBoost is a pure monitor feature it can officially only be activated using NVIDIA graphics hardware, but since 2D LightBoost is becoming more and more popular in gamer circles, ways have been found to activate LightBoost also without needing additional NVIDIA 3D equipment (see LightBoost Utility, but be aware that this utility does not work with the new Z-series of the BenQ monitors).

Early 2014: The best 24" LightBoost monitors appear to be the BenQ XL2411T, the BenQ XL2420T, and the ASUS VG248QE. Note that these monitors support refresh rates up to 144Hz but LightBoost is only supported at refresh rates of 100Hz or 120Hz (older BenQ's, even of the very same type, might not support 144Hz). The 27" equivalents to these monitors are said to have a slightly better image quality. Be aware that the market regarding fast monitors is very much in a flow these days. BenQ has recently released Z-versions (e.g. the XL2411Z) that adopt a 2D motion blur reduction technology in addition to LightBoost. EIZO has announced the DuraVision FDF2405W (professional) and released the FORIS FG2421 (consumer), both of which employ 240Hz VA panels (input max. 120Hz) with strobed backlight.

At a glance...

Note that LightBoost is not well advertized, neither by NVIDIA nor by the monitor manufacturers, and hardly any official information can be found about which features are actually part of LightBoost. Therefore, the following list might contain features which are not implemented in all LightBoost monitors.

How it works

  1. The LED backlight is briefly flashed only once per refresh cycle. Besides other benefits, this helps alleviating motion blur.
  2. The backlight flashes occur at the end of each refresh cycle, thereby hiding the settling of the pixels (as characterized by the LCD's response time) in the dark.
  3. The backlight luminance (LED current) is higher than normal. This helps to compensate for the shortness of the backlight flashes.
  4. The updating of the screen (i.e., writing new pixel values) is accelerated so as to leave the pixels more time to settle before the backlight is flashed.
  5. The pixel settling is accelerated by use of overdrive techniques. The amount of overdrive is carefully adjusted to the vertical pixel position in order to compensate for the different settling times available for different pixel lines.

Downsides

  1. LightBoost requires an LC panel with sufficiently low response time, which currently is only provided by TN-panels. Unfortunately, TN-panels have a number of disadvantages, like a low native color resolution of only 6 bits per color channel and a relatively small viewing angle.
  2. The accelerated update of the LC panel, i.e., the reduced time to properly "charge" the pixel cells, may come with a decreased image quality. This may become noticeable, for example, by subtle line patterns, possibly being "enriched" with temporal components.
  3. The maximal average luminance output is usually lower than in normal mode.
  4. As far as the switching dynamics are concerned, the display quality degrades from the top of the screen to the bottom, because pixels at the top have more time to settle before the backlight is flashed than pixels at the bottom. This is true even if sophisticated but still limited overdrive techniques are applied.
  5. The flicker percept might be stronger with LightBoost as compared to, for example, CRTs, because with LightBoost all the pixels light up at the very same time whereas on CRTs they light up sequentially. Moreover, the light is shut off completely during the times between the backlight flashes, whereas the phosphor in CRTs decays gradually.
  6. There is an inevitable increase in the average time lag as compared to CRTs or LCDs with normal backlight.
  7. The color quality (gamut, naturalness) is rather low due to the TN-type panel and the backlight being made of white LEDs.
  8. The lifetime of the LED backlight might be shortened by the increased stress imposed upon the LEDs when operated in LightBoost mode.

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