LG 55 B4 vs Xiaomi S Pro 2026

The brightness results in HDR materials LG B4 are very good. It is true that none of them exceed 1000 nits, although the luminance stability is excellent and looks practically the same in every scenario. The only moment where the tested television performs worse is the last scene, although this should not come as a surprise. Large frames filled with a lot of white have always been, and will likely continue to be, somewhat of a weakness for OLED televisions. However, the combination of perfect contrast, black levels, and brightness in the LG B4 allows for a full spectrum of the HDR effect. Additionally, the incredibly high coverage of the DCI-P3 colour gamut, which reached 99%, deserves recognition. As a result, colours look incredibly vibrant and stunning.

When it comes to HDR quality, the Xiaomi S Pro 2026 is undoubtedly a very bright television. On our synthetic measurement patterns, we were able to achieve peak brightness of around 1400 nits. This result is not only very good but quite spectacular, considering the price of this model. However, as we always say, our editorial team values measurements and the viewing experience of content that people watch on a daily basis – from movies to series. So let’s analyse how Xiaomi performs with film material. The result is, unfortunately, quite mixed. When very bright scenes appear on screen, the S Pro 2026 truly shows its full capabilities and can achieve a real 800-1000 nits on bright elements. Moreover, even smaller objects can "burn" the eyes – in scenes from the movie Sicario 2, small metallic parts of the helicopter were really vivid. The problem is – and here the story comes full circle, returning to our contrast assessment – that in such scenes, we can’t count on absolutely cinematic black. In our opinion, this compromise is too significant; the high visibility of details in bright sections should not come at the expense of such a substantial drop in blacks. And even though the HDR effect can create a stunning impression here, it’s important to remember that when very challenging, mixed scenes appear on screen, we may feel a slight disappointment. Precisely the one we mentioned in the previous paragraph regarding issues with dimming in HDR mode. As a consolation, it’s worth adding that the S Pro 2026 is equipped with an additional PFS filter (similar in function to a QLED layer), which effectively broadens the colour gamut coverage. As a result, measurements showed DCI-P3 coverage reaching 94%. This gives us confidence that in most colourful scenes, the image will look rich and properly saturated.

The best factory mode prepared by the manufacturer is "Filmmaker," and we used it throughout the entire testing procedure. We must admit that the unit we received straight out of the box had quite decent colour reproduction. The biggest issue in both SDR and HDR content turned out to be white balance. In the former, there was a strong dominance of red, resulting in a noticeable yellow tint in the displayed image, particularly evident on skin tones and whites. In high-quality materials, this colour was also pronounced, but due to a lack of blue, there were also signs of green visible. Besides these shortcomings, we also encountered issues with greyscale and the colours themselves.

Of course, all our measurements were conducted in "Film" mode, which is typically the best and most faithful choice we get straight after taking the TV out of the box. And to put it bluntly: while this is the best mode, it is still very far from perfect. Above all, the TV has a clear tendency to give the picture a cool, blueish tint – this is due to poorly set colour balance. Additionally, there is the issue of how the S Pro 2026 manages its brightness straight out of the box, which results in an over-saturated image. These two flaws contribute to really significant colourimetric errors (Delta E). In HDR content, they could double exceed our expected error scale of "10" (i.e. reaching values close to 20). Just to remind you – the threshold of perceivable error by the human eye is a Delta E value of around 3. Results at the level of 20 mean that the image significantly deviates from what the director intended.

LG B4 has been providing very advanced calibration tools in its TVs for years. We can even say that as the only manufacturer on the market, it allows for such deep intervention in image adjustment. Thanks to these, we were able to calibrate the device so well. The evidence of this is the extremely low deltaE errors, which can be said to stand at a reference level. Both SDR and HDR materials now look exactly as the film director intended. It is no coincidence that TVs of this brand are most often used as preview screens for various graphic or post-production studios.

So how does the S Pro 2026 perform after our calibration process? We must admit that after calibration, the TV becomes a really enjoyable device for watching everyday content. As you can see in the charts, in HD (SDR) material, both white balance and gamma values have been brought to nearly perfection. Most importantly, colourimetric errors have become practically invisible to the human eye. In this scenario, the S Pro 2026 is simply a great TV that, after professional calibration, can provide a lot of joy from viewing. However, it is worth noting clearly – our efforts did little to help in 4K HDR mode. Despite the calibration, the TV still interprets the image quite strongly in its "own way," which is clearly evident in the measurement of the EOTF curve (brightness tracking). It's a bit of a shame because it shows that the problem lies not with the panel itself, but with the software. Poorly refined image management algorithms in HDR content can, unfortunately, rule this TV out for many more discerning users.

In this paragraph, we will take another look at the tonal transition smoothing feature, but we will also check how the TV handles lower quality material. As we have managed to check, the setting responsible for smooth gradation works quite effectively, although it has its weaker moments. While the feature works well with SDR content, it becomes less useful with HDR content. Even at the lowest of options, it blurs essential details, so we advise against using it.

The image scaling on LG B4 is rated fairly moderately positively. Although there is no edge splitting, the image itself is naturally "soft". We can change this by adjusting the sharpness slider.

Let's start with the issue we raised in the previous paragraph: can a TV even fix the problem of terrible tonal transitions in dark scenes? Theoretically yes – in the menu, we find a feature with the promising name "Colour Contour Removal." Well, "theoretically." Unfortunately, in practice, this setting – regardless of which of the three power levels is chosen – yielded absolutely no real results. So we are dealing with a feature that practically only exists in the menu. Moving on to the quality of upscaling (scaling from a lower resolution to 4K), unfortunately, we have more bad news for you. The S Pro 2026 handles this task very poorly. Interestingly, the phenomenon of "overscan" (slight image cropping) is not a major issue here. The problem is that the TV simply shows a very raw, unprocessed image. Its attempt to boost the signal to a higher resolution looks simply dull and lacks any "intelligent" enhancement. There's no denying it – the entire digital image processing is the true Achilles' heel of this model.

The maximum refresh rate we can set on the LG B4 is 120 Hz. This is the absolute minimum for those who require high image smoothness. The manufacturer has implemented a multi-level motion smoother called "TruMotion". It has been divided into two separate sliders that adjust the sharpness of moving images (De-Blur) and stuttering (De-Judder). Both sliders can be set in the range from 0 to 10, with each level affecting the degree of smoothness, so everyone can find their sweet spot.

The LG OLED B4 panel features an average response time of 0.1 ms (which directly results from our measurements), allowing for an incredibly clear image, unattainable for LCD TVs, which have response times of even several milliseconds. This can be clearly seen in images from the "UFO Test", showing no trace of blur trailing behind the object.

On paper, the specifications of the S Pro 2026 look impressive. The television is equipped with a native 144 Hz panel, capable of displaying images at up to 288 Hz in a dedicated gaming mode. These are incredible results, but what we were most interested in, in the context of everyday use, was how the TV handles motion blur and how the picture looks at 120 Hz. After all, this is the frequency used today by consoles such as the PlayStation 5, Xbox Series X/S, and it is desirable for sports fans. Generally, the panel "holds up". The matrix is quick enough to meet these challenges, and objects displayed at a native smoothness of 120 Hz are rendered correctly. When it comes to software, the TV is equipped with motion smoothing technology, but with a key caveat – it only works for input signals up to 60 Hz. This means it's mainly suitable for traditional TV, movies, and series. With it, we can adjust the smoothness of the picture to our own preferences – ranging from a very smooth, "theatrical" approach, to setting the slider at "zero" and maintaining a fully cinematic character.

The LG B4 television is equipped with four full-fledged HDMI 2.1 ports with a full bandwidth of 48Gbps. All functions corresponding to this standard activated without any issues, and throughout the entire testing procedure, they caused no problems. The combination of such extensive functionality and low input lags leads us to say that the tested television is truly designed for gaming. This is not surprising, considering that the manufacturer has always placed great emphasis on this. Therefore, we can enjoy both a properly implemented HGIG mode and gameplay in Dolby Vision with low latency. Such a tandem will surely attract the attention of all passionate gamers for whom quality is the most important.

A standard feature in televisions from the Korean manufacturer is also the implementation of GameBar, allowing for quick adjustments of settings "on the fly," without the need to exit the game. It also enables image adjustments for individuals with visual impairments, which is an extremely nice touch. Another important piece of information is that when the VRR technology is turned on, we will not experience a drop in contrast. This is, of course, due to the construction of the panel and the lack of conventional backlighting. However, it is normal for shades of grey to flicker slightly, although this is a characteristic feature of this function regardless of the manufacturer and the television.

In summary: The LG B4, like all OLEDs from the manufacturer equipped with 120Hz panels and HDMI 2.1 ports, creates a harmonious whole with the console. In practice, it is a complete television, and if we expect the highest possible efficiency in gaming, the B4 will be the ideal choice.

For gamers, the Xiaomi S Pro 2026 is on paper an almost perfect proposition. It has been equipped with two HDMI 2.1 ports, which allow us to unlock (although these options are somewhat hidden in the menu) the full suite of features: ALLM, VRR, and, crucially, the ability to operate in 4K at 144 Hz. This last feature should particularly please owners of powerful PCs. The TV also has something resembling a gamer panel – and while it’s hard to call it a full-fledged "Gamebar," it does its job by displaying key information. It’s just a shame that in its default form, it covers a relatively large part of the screen.

The biggest problem we have with this model, however, concerns how the S Pro 2026 handles games in HDR mode. To put it bluntly: it doesn’t handle it well. Due to the poorly implemented HGiG feature (the HDR tone mapping standard for games), during the initial HDR calibration on the console, it’s very easy to "blow out" the image. If someone is unaware of this software flaw and follows the on-screen instructions, they will simply set the picture incorrectly, with burnt-out details in bright areas. Another significant issue is the Dolby Vision mode for games. While it works, it generates such a high input lag that it becomes noticeable in dynamic titles. (You can check all our lag measurements in the paragraph below). In summary: Generally, this is a really very good screen for gamers, but with one small caveat. We would rather avoid HDR mode on it – unless we decide to manually set the brightness slider on the console "by eye," completely ignoring the tips from the console's pictogram.