Project: Spectrum | BFI Coming to Spectrum OLED!


Hey everyone,

It’s time for another update on Spectrum’s development. This time we’ve got exciting news about Black Frame Insertion (BFI), a feature that is often asked for, but very hard to find on OLED gaming monitors. But what is it all about? Why do we want it? Can we implement it? Let’s find out!


Eye-tracking blur

Objects in the real world move without any intervals – after all, the real world does not have a frame rate or refresh rate. So, when our eyes track a moving object, we always see it exactly where it is (Figure 1).

Modern flat-panel displays work by showing a frame, then holding that image until it is ready to display the next. All the pixels change their state in unison, and the next frame is held, and so on. This process is called ‘sample and hold’. When representing a moving object on a screen, each new frame shows the object in a new position (Figure 2). The human brain tries to make sense of this, and as long as there is enough information to go off (a high enough frame rate), we interpret these objects jumping across the screen as objects in motion.

However, only at the instant a new frame appears on the screen, does it appear in the right spot. From then on, our eyes expect the moving object to keep moving, even though the screen shows it in the same place until the next frame is shown. This mismatch between the location on the screen and the location where your eye expects the object to be, is perceived as blur (Figure 3).

eye-tracking blur graphs-combined 1

Reducing persistence

High-refresh rate displays, when combined with powerful graphics cards that can generate more individual frames, lessen the impact of this eye-tracking blur. After all, the more often a new frame is loaded, the more often the location of a moving object is shown spot-on. And the shorter the time until the next frame is loaded, the lower the average discrepancy between a shown object and its intended location (Figure 4).

In contrast to sample-and-hold displays, old CRT monitors draw lines on the screen that start to fade as soon as they appear. And while there are many benefits to modern monitors, this is one area in which the old tube-based screens take a win: this constant re-building of the screen means that your eyes only see a moving object on the screen in a certain position, when it’s actually supposed to be there (Figure 5).

This effect can be mimicked on LCD screens by turning the backlight on and off rapidly (called ‘backlight strobing’). Much like the shutter on an old video projector, turning the backlight off limits the amount of time each frame is shown on the screen. Having the image persist for a shorter time, reduces the amount of eye-tracking blur (Figure 6). It’s not perfect, but we’re getting closer.

eye-tracking blur graphs-combined 2

The main trade-off to this technique, is in the screen’s brightness. Reducing the time that the backlight is active also reduces the amount of light the screen can emit. Our IPS-based Spectrum models come with OSD settings to control how long each frame is shown before the backlight turns off again, so users can find the perfect balance between brightness and motion blur reduction.

Strobing on OLED technology


Of course, the individual sub-pixels of our new monitor’s OLED panel emit their own light, removing the need for a backlight module. Even so, OLED screens can still apply the same concept of reducing persistence to reduce eye-tracking blur. In this case, instead of the backlight, the OLED sub-pixels themselves can be turned off to create the ‘shutter’ effect. And because of the exceptionally low response times, this can be done almost instantly.

Ideally, we would offer similar settings to those on our IPS monitors, where you can set your own ideal balance of brightness and motion blur reduction. However, this is where we run into some technical limitations of our panel. Unlike our IPS monitors, where the scaler individually controls the LCD panel and the backlight unit… …there is no backlight unit to control.

This means we need to signal the OLED layer of the panel to turn off its light in the middle of a refresh cycle. Sadly, even though the panel manufacturer tested this during the development of the panel, they found that it required a lot of additional internal wiring, increasing the cost significantly. Without this support from our display hardware, we cannot offer our preferred strobing implementation.

Black frame insertion

That does not mean we are completely out of luck: even though our panel cannot turn off the panel in between refresh cycles, we can still tell the pixels to turn off as part of a refresh cycle. By alternately sending the panel a new image frame, and then a fully black frame, the result is similar. This method of inserting black frames is appropriately called ‘black frame insertion’ (BFI). Blur Busters has an excellent Test UFO demo that simulates the effects of BFI on eye-tracking blur here.

The good news is that by working with our scaler manufacturer, we were able to successfully implement this alternate form of image strobing. The bad news is that this method is more limited.

For one, we are using actual refresh cycles to insert the black frames. The more black frames we insert, the fewer image frames we can show. So even though we have this working at up to 240Hz, we can only display up to 120 unique frames – the other 120 frames are necessarily black (Figure 7). This means that while BFI is active, Spectrum effectively behaves like a 120Hz monitor. Albeit a 120Hz monitor with very little motion blur!

Another limitation of this method is that we don’t have nearly as much control over that balance between brightness and blur reduction. With every other frame, image persistence is 50%, and that’s it. Our firmware team is working on settings that allow a new frame every third (Figure 8), or every fourth refresh cycle (Figure 9), with the frames in-between being black. This would offer settings for 33% and 25% persistence respectively, and would further reduce motion blur. Of course, this would now not only reduce the brightness, but also the maximum frame rate (in these cases, down to 80 and 60fps).

eye-tracking blur graphs-combined 3

If that’s not your cup of tea, there is of course always the option to leave it off. Without BFI, you unluck the full potential of the panel with a 240Hz refresh rate and maximum brightness. That said, we are proud and excited to offer this implementation of strobing on our OLED monitor. Despite the limitations the results speak for themselves, and any game that doesn’t run at more than 120fps will look amazingly blur-free on Spectrum.

More to come

At the moment we have BFI working at up to 120fps, but our team is still figuring out whether they can get it to work in combination with variable refresh rates. We will of course let you guys know once we have made more progress. Thank you for tuning in and let us know what you think!

DOUGH Subscribediscordtwitterfacebookinstagramyoutube


Weird suggestion and maybe not exactly the best solution but… Have a setting to allow BFI to work at supported Refresh rates with VRR is active. If the fps stays at a constant 60 fps, 80 fps or 120 fps begin to strobe but the moment the timing is off, allow the monitor to blur and decrease brightness to compensate the lack of a black frame. Either that OR enable per application profiles as a windows app (or OS agnostic app) where if it detects a certain game or app a user can set spectrum OLED to do fixed strobe at that specific timing without turning the screen off and back on (like you normally find other panels do when you are changing between resolutions or refresh rates).

I’d also add the “added cost” of adding those wires to enable proper BFI for 240 hz on this oled would be easily worth it for the niche audience that will be selling it for. There are people that spend thousands of dollars on a mint condition CRT for motion clarity alone. Selling an OLED spectrum with VRR + BFI that works from 50 hz - 240 hz would easily sell for $1600 given this is the only monitor that would be able to do that AND be glossy at the moment. Without BFI or the fact that this monitor is glossy, most people will turn tail and buy the corsair xeneon 27QHD240 with similar specs. Hardware unboxed already almost choked when they had to mention how good the blur reduction mode was on the spectrum 4k @ 144 hz was that they actually had to mention it would be their top pick if strobing was a priority (despite them strongly disagreeing with the delivery of your monitors, the late deadlines, etc).
I know this comment may get deleted but I do want to stress that if you have a unique monitor that offers a feature set that no one else has, you can charge the premium and other people have to stomach and wait for it. However, as we continue the year more and more competition is coming out in the 240 hz oled space and customers would be more willing to deal with other well known companies than deal with dough until you do right by the early backers who wanted something truly special.

Hi @Liquidshadowfox,

The added cost portion is not something that we have control over, as we are talking about the internal wiring as part of the panel.

We are aware of the feature sets that can set us apart from the competitor, that is why we are trying our best by implementing features that our competitors do not have. BFI being one, for example (despite its limitations).

I’m hyped for this now. Thanks for listening to your community (me and @Liquidshadowfox specifically :pray:) and brining us this feature. I’ll be putting my order in once the shipping starts. Can’t wait to see what this tech will look like in person.

I personally think that the 120fps is acceptable considering the technologies limitations and that none of the big dogs are even attempting to bring us BFI in this generation of monitors. As long as the firmware is stable this time I think it will be a big hit.

Just hope the reviewers don’t write it off due to “reasons”. It’s still great to get some real feature options that actually matter to buyers.


Listening to and acknowledging feedback for features is great

If only they actually shipped correct, working products, fulfilled warranty claims, and honored their refund policy

Hello there. I am currently using an LG 27 OLED Ultragear monitor and faking BFI at both 120Hz and 92Hz for stereoscopic 3D content. I am very excited to hear that this will be built into the monitor, and will purchase one as soon as they are available.

I was hoping that you will implement BFI at alternative rates, in particular 92Hz. This rate for me is especially important because I can run HFR movies at their native 48Hz for an extremely smooth 3D HFR experience. I have used frame interpolation software to bump 24Hz 3D movies (Tron Legacy, Avatar etc.) to 48Hz and the experience is incredible.

Would love to share more with you. For more info about what we are doing, please visit

Thank you!

Hi @peter, and welcome to the community!

Specifically 92Hz? Thats interesting to know. I am not entirely sure if this is doable because of the limitations mentioned on the original post, but I will give the team a heads up just in case.

But I’m not sure if I understand what you meant by “faking BFI” what did you do exactly?

Thank you for sharing!

Hey Cas, I made an error in the numbers, I will explain better:

At 240Hz, I am injecting a black frame every other frame, bringing it down to 120Hz visible frames. I have a hardware device that can detect the frames and know which visible frame is left and right, so effectively I can trigger active shutter glasses to show one frame to the left eye and another to the right, which now brings down the frame rate to 60Hz.

I’m calling it fake BFI because it’s inefficient; the CPU and GPU are running at 240Hz, and I have to do some work to claim those timeslices back in a meaningful way. What once ran perfectly on a 120Hz display with BFI (i.e. the LG C1 OLED TV) is now eating up cycles because I have to run at 240Hz. It hasn’t been too big of an issue, but it’s not ideal.

So, for HFR movies, the frame rate is 48Hz stereo. Therefore, I can set the LG Ultragear 27 monitor to 192Hz, inject black frames, get it running at ‘96Hz’ (not 92, that was my numeric mistake in the previous message). With the tagging of left and right images as before, the rate is now stereoscopic 48Hz, and we can watch HFR movies at the right frame rate (and it is silky smooth since it matches the display output).

So ideally, I would love to see BFI be turned on for any monitor frequency under 240Hz, possibly the frequency needs to be divisible by 2 in the implementation? That way, when then the display is actually running at 192 + BFI on, the computer will read it as 96Hz.

Thank you!!

1 Like

Hi there,

I see where you are getting at. Let me get this to the team.

1 Like

From what I understand, Windows only sees 120Hz whenever the Dough monitor is doing 240Hz BFI.

It’s basically doing it at the hardware side, so Windows just sees the visible-frame refresh rate, and just needs to transmit 120 refresh cycles over the DisplayPort / HDMI cable. The scaler/TCON is the part that is inserting the black frames. Basically a hardware based scan-conversion + black-frame-insert. No CPU or GPU is used.

Even some 240Hz LCD monitors do automatic scan conversion, e.g. when doing 60Hz or 120Hz on a 240Hz LCD. This is because some 240Hz LCD’s are fixed-horizontal-scanrate, and is the biggest reason why some of them more laggy at 60Hz and 120Hz, than native-60Hz and native-120Hz panels.

So this is simply a piggyback on something a panel is already doing, as all 240Hz OLEDs have to convert 60Hz and 120Hz to 240Hz anyway (even without BFI) so adding BFI is essentially “free”, hardware-side.

This is actually how many LG TVs do it too – hardware-based “monitor firmware level insertion of black frames” system. However, what is different is that the LG OLED monitor panels were originally not programmed to have BFI in the general reference design, but the engineers at Dough’s firmware vendor (RealTek) figured out how to add BFI at the monitor firmware level.

What’s brilliant here, however, is that this confirms (as I already knew) that OLED BFI is addable by a third-party firmware vendor (Realtek), that Dough hired for firmware modifications, meaning BFI can be added by a third party other than panel vendor (LG).

Also, 48 x 2 = 96. It probably is easy/possible to do the 96, and I know RealTek can do it (actually, it would be a Windows 48 Hz mode). But it will be Dough’s decision whether or not they proceed with BFI for odd refresh rates.

Nontheless, it is my public recommendation to all LG OLED vendors that want to support BFI, to try to add support for it at all refresh rates below 120Hz as well, all the way from ~47.9 Hz thru 120Hz signal refresh rate, even if the internal panel refresh behavior continues to be a 1/240sec scanout, out of necessity.

I hope this generically clarifies the OLED BFI workflow for you.

Also, Athanos I see you’re a business as well. If you have unusual display-temporal workflows, my consulting services are also available, – There are several clients whom I’ve worked with to add stereoscopic 3D glasses support to existing OLEDs for things like medical industry and other applications. It should be possible for third-parties to implement frame-sequential stereoscopic 3D glasses with Dough’s monitor, using it firmware-side BFI, without needing to use Windows application-level BFI.

Mark Rejhon
Founder, Blur Busters / TestUFO
Fair Disclosure: Currently on paid contract with LG Display Korea for general 240Hz OLED motion metric testing. Due to this panel-level contract, it also consequentially means I end up working with multiple OLED monitor brand names that utilizes LG OLED panels – including Dough.