NVIDIA Announces ULMB 2 — Improved Motion Blur Reduction

A Better Strobe Backlight Algorithm for Gaming Monitors

Long-time Blur Busters readers knows that Blur Busters started because of strobe backlight systems, including our famous NVIDIA LightBoost HOWTO from more than a decade ago!

Blur Busters has been longtime textbook reading education for mainstream media. As a display motion blur website with a high reputation (over 25 research papers cite us), the mainstream media frequently read our website as a simplified fact-check on display motion blur science. Therefore, our article mainly provides technical commentary that covers areas that nobody else does.

A Better Strobe Backlight Algorithm for Gaming Monitors

NVIDIA has a news release about improvements to G-SYNC monitors, including ULMB 2 and overdrive improvements. Needless to say, the ULMB 2 caught the attention of our name sake Blur Busters, being that ULMB stands for Ultra Low Motion Blur.

Blur Busters Fact Check: Refresh Rate Equivalences

NVIDIA claims that ULMB can produce an effective motion clarity similar to a 1000Hz monitor.

NVIDIA’s claim is correct specifically for display persistence, during eye tracking situation. This is also scientifically correct for the majority of good-quality strobe backlights capable of 1ms pulse widths, including Blur Busters Approved.

There are caveats though. There are four scientific considerations:

1. Strobe Pulse Width of 1ms or Less

   Motion blur is pixel visibility time, as explained at Blur Busters Law: The Amazing Journey To Future 1000 Hz Displays. Pixel visibility time is frametime on flicker free displays including sample-and-hold displays. However, pixel visibility time becomes pulsewidth on strobed displays. Therefore, good 1ms strobe flashes at lower Hz and framerate with no strobe crosstalk, can produce similar motion clarity as 1000fps 1000Hz sample and hold display with a 0ms GtG pixel response.
   
   

2. Frame rate = refresh rate = strobe rate

   To maintain the “1000Hz look” at a low refresh rate with strobing, it is critical to achieve frame rates at least matching the strobed refresh rate. This is necessary to avoid the the double images effects caused by framerates being below Hz. This effect is similar to the old CRT/plasma 30fps at 60Hz. Scientifically, this is caused by our analog-moving eyes being in different positions during flashes of same unchanged frames — see TestUFO double-image animation (view with strobing disabled).
   
   

3. No visible strobe crosstalk caused by slow LCD GtG;
   

   Strobe crosstalk is caused by incomplete pixel transitions between backlight flashes. Pixel transitions with strobe backlights, need to be fast enough to complete in the blanking interval between refresh cycles. This is very difficult at higher LCD refresh rates. 360Hz uses refresh cycles that last only 1/360sec, which is 2.78 milliseconds. This is often faster than LCD GtG is available.
   

4. Eye tracking on moving objects

   Strobe backlights has the biggest visibility improvement with full screen movements, such as panning, scrolling, and mouselook turning. In addition, it is mainly visible when eye-tracking the screen motion, rather than a permanent fixed-gaze at screen crosshairs. (This is important to note that strobing benefits different games, This is partially why strobe backlights is more popular in certain games than others; the Rainbow Six esports champion from a few years ago, used strobing). Here is an animation, meant to be viewed on a non-strobed display, that demonstrates display motion blur that only occurs with eye-tracking. See the difference in background motion blur behavior between the two UFOs:

Non eye-tracked motion is not as smooth as true 1000fps 1000Hz monitor, from the perspective of The Stroboscopic Effect of Finite Frame Rates.

However, the persistence-related display motion blur of the best strobe backlights (not just ULMB 2) is indeed as good as 1000fps 1000Hz, as long as all four considerations above are concurrently met.

Strobe backlights produce excellent motion blur reduction, because it overcomes the LCD sample-and-hold effect. Display motion blur (during eye tracking) is based on pixel visibility time, as seen in TestUFO tests.

Making ULMB Available at Max Hz: Custom Overdrive Gain On a Per Pixel Row Basis

Historically, NVIDIA prevented ULMB from being available at maximum Hz, due to the problems of strobe crosstalk.

NVIDIA re-added an engineering enhancement to make ULMB available at maximum Hz, without excessive strobe crosstalk.

ULMB 2 resurrects an algorithm that was originally used for LightBoost over ten years ago, as several engineers have noticed (Display-Corner states “…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…“)

Some very fast LCD panels no longer urgently required this, especially with Large Vertical Total tweaks on supported panels. However, current refresh rates such as 360 Hz, now require this technique to speed up LCD GtG sufficiently enough.

Firmware Updates Available for Some Existing 360 Hz G-SYNC Monitors

NVIDIA also announces that firmware updates are going to be available, to add ULMB 2 to several 1440p 360Hz panels:

The firmwares containing ULMB 2 are being released at Computex 2023 Taiwan. Several future 360+ Hz monitors with G-SYNC native, will likely include ULMB 2 as standard.

Blur Busters commends the existence of firmware updates, as gaming monitors are getting more complex as more time passes, and firmware updates are frequently released to fix issues on gaming monitors.

Commentary about Robot-Arm Pursuit Camera

Another thing that caught Blur Busters attention, is another method of a display motion blur measurement pursuit camera. A moving camera simulates moving eyeballs, to capture WYSIWYG perceived display motion blur into a photograph.

We have a display motion blur measurement pursuit camera invention (that is peer-reviewed by a NIST.gov, NOKIA and KELTEK researchers) that is currently used by over 500 content creators (total viewership of 100 million+), now usable by indies using a hand-waved smartphone, but the use of an accurate robot arm, is quite innovative.

However, this is a brand new technique of a pursuit camera that is extremely clever and capable of real-world game pursuit capture! We observed that it is able to be programmed to follow a game mouse-look automatically in a framerate-independent manner, since it uses a LDAT blip system (likely a GPIO connection) to help assist its tracking along the average (floating) pixels/sec motion.

We saw a video of this in action during mouselook in a real video game, and were quite impressed with its tracking accuracy as well as its relatively-WYSIWYG motion blurs and ghosting.

Blur Busters Recommendations on Future Improvements on ULMB 2

Since ULMB 2 is firmware updatable, we have additional suggestions to NVIDIA and vendors:

1. NVIDIA should support strobe at any fixed refresh rate.
   To expand the market for motion blur reduction, all users other than esports need to be accomodated.  A significant portion of the Blur Busters audience have asked for additional features in a strobe backlight, including the ability to run at any refresh rates, rather than presets.  For example, the ViewSonic XG2431, a Blur Busters Approved monitor, supports fixed-Hz strobing at any custom refresh rate from 59Hz through 241Hz.

   Note: Some engineers incorrectly claim this is not possible. However, Blur Busters has successfully invented a method, to strobe-tune all refresh rates, by applying an algebraic regression formula to curve-fit tuning data measured from multiple refresh rates. In fact, this even can be done on a per-pixel-row basis, creating a custom formula (derived from algebraic regression to curve-fit photodiode data) that also now includes a Hz variable and a Vertical-Total variable, to calculate the correct overdrive gain value on a per pixel row basis.

2. NVIDIA should support retro refresh rate strobing, at least via an easter-egg setting.
   The gaming monitor market is not just for gaming. It is also used by many other people, including people who play retro content and video content (e.g. 60fps and 120fps content). Monitor sales are falling, and with the mainstreaming of 120Hz (iPhone, Galaxy, XBox, PlayStation), the gaming monitor market needs to expand by offering strobing at any Hz including non-esports refresh rates, to increase sales of motion blur reduction systems.

   Note: Although the flicker of 60Hz single-strobe is problematic for many, there are a large sub-audience within Blur Busters who get more eyestrain from motion blur than from flicker. Also, as long as 60Hz single-strobe is only used within games (rather than Windows), the eye-strain becomes less of a problem. There are mitigations such as hiding this setting except to advanced users (easter egg settings or hidden advanced “Minimum Strobe Hz” setting as well as appropriate warnings “Warning: This ULMB refresh rate may flicker. Discontinue use if you get eyestrain.” similar to those found for 60Hz televisions)

3. NVIDIA should contact Blur Busters to apply for the Blur Busters Approved logo on ULMB 2
   ULMB 2 would easily meet Blur Busters Approved criteria, as ULMB 2 is already fantastic strobe quality, especially on TN and IPS panels using non-KSF backlights. There are only minor missing requirements of ULMB 2, that would be necessary to fulfil in order to qualify for a license for the Blur Busters Approved logo.

   Note: To contact Blur Busters about the Blur Busters Approved logo certification programme, please reach out at services.blurbusters.com. We now have both an LCD and an OLED version of the certification programme.