LG 55 B4 vs Xiaomi S Pro 2026

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

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 generate peak brightness of around 1400 nits. This result is not only very good but truly spectacular, considering the price of this model. However, as we always emphasise, for our editorial team, measurements and the experiences from the content viewed on a daily basis - from films and series - are more important. So let's analyse how the Xiaomi performs with film material. The result is, unfortunately, quite mixed. When very bright scenes appear on screen, the S Pro 2026 really shows its full potential and can achieve a real 800-1000 nits in bright elements. Moreover, even smaller objects can "burn" the eyes - in scenes from the film Sicario 2, small metal elements of the helicopter were truly vivid. The problem is that - and here the story comes full circle back to our contrast assessment - in such scenes we cannot count on absolutely cinematic black. In our opinion, this compromise is too great; high visibility of details in bright areas should not come at the cost of such a significant boost to black levels. And although the HDR effect itself can make a stunning impression here, it is essential to remember that when very challenging, mixed scenes appear on screen, we might feel a slight disappointment. Exactly the one we mentioned in the previous paragraph regarding issues with dimming in HDR mode. As a consolation, it is worth adding that the S Pro 2026 has been 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 up to 94%. This gives us confidence that in most colourful scenes, the image will appear rich and appropriately saturated.

The best factory mode prepared by the manufacturer is "Filmmaker," which is exactly what we used throughout the entire testing procedure. We must admit that the unit we received out of the box had quite good colour reproduction. The biggest problem in both SDR and HDR content turned out to be white balance. In the former, a strong red hue was evident, causing the displayed image to have a pronounced yellow tint, particularly noticeable on skin tones and whites. In higher quality materials, this colour was also accentuated, but due to a lack of blue, there were also signs of green visible. Apart from these issues, we also encountered problems with grayscale and the colours themselves.

Of course, all our measurements were carried out in "Film" mode, which is typically the best and most accurate choice we get straight out of the box. It needs to be said plainly: although it is the best mode, it is still very far from ideal. Firstly, the television has a clear tendency to impart a cool, bluish tint to the image – this is due to a poorly set white balance. Additionally, there is the issue of how the S Pro 2026 manages its brightness straight out of the box, which results in an overly vivid image. These two flaws contribute to truly significant colourimetric errors (Delta E). In HDR content, they were able to exceed our anticipated error scale of "10" by twofold (meaning values close to 20). As a reminder – the threshold for perceivable error by the human eye is a Delta E value of around 3. Results at the level of 20 indicate that the image significantly deviates from what the director intended.

LG B4 has been providing very advanced calibration tools in its televisions for years. We can even say that as the only manufacturer on the market, it allows for such deep intervention in image adjustment. It is thanks to these tools that we were able to calibrate the device so well. Evidence of this is the extremely low deltaE errors, which can be said to be at a reference level. Both SDR and HDR materials now look exactly as intended by the film director. It is no coincidence that televisions 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 procedure? We have to admit that after calibration, the television becomes a really very pleasant device for watching everyday content. As you can see in the graphs, in HD (SDR) materials, both white balance and gamma values have been brought to nearly perfection. Most importantly, colourimetric errors have become practically unnoticeable to the human eye. In this scenario, the S Pro 2026 is simply an excellent television that, after professional calibration, can provide a lot of enjoyment from watching. However, it is worth clearly noting – our efforts have not helped much in 4K HDR mode. Despite the calibration, the television still interprets the image quite strongly "in its own way," which is clearly visible in the measurement of the EOTF curve (brightness tracking). It’s a bit of a shame, as it shows that the problem lies not in the panel itself, but in the software. Underdeveloped image management algorithms in HDR content can, unfortunately, rule out this television for many more discerning users.

In this paragraph, we will take another look at the function for smoothing tonal transitions, but we will also check how the television handles lower quality material. As we have managed to verify, the setting responsible for smooth gradation works quite efficiently, although it has its weaker moments. Just as the function works correctly in SDR content, it becomes rather useless in HDR content. Even at the lowest of the options, it blurs essential details, which is why we advise against using it.

The image scaling on LG B4 is rated rather moderately positively. Although there is no edge doubling, 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 the television actually fix the problem of dreadful 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, in practice, only exists in the menu. Moving on to the quality of upscaling (scaling the image from a lower resolution to 4K), unfortunately, we have more bad news for you. The S Pro 2026 performs very poorly at this task. Interestingly, the phenomenon of "overscan" (slight cropping of the image) is not a major issue here. The fact is that the television simply displays a very raw, unprocessed image. Its attempt to upscale the signal to a higher resolution looks simply lacklustre and lacks any form of "intelligent" improvement. There is no denying it – the entire digital image processing is the real Achilles' heel of this model.

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

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 televisions, whose response times can be as high as several milliseconds. This is clearly evident in the pictures from the "UFO Test", showing no trail following the object.

On paper, the S Pro 2026 specification looks impressive. The television is equipped with a native 144 Hz panel, with the ability to display images at up to 288 Hz in a dedicated gaming mode. These are amazing results, but what interested us most, in the context of everyday use, was how the television handles motion blur and how the image looks at 120 Hz. After all, this is the frequency used by consoles like the PlayStation 5 and Xbox Series X/S, and it is desired by sports fans. Generally, the panel "holds up". The matrix is sufficiently fast to meet these challenges, and objects displayed at native 120Hz fluidity are shown correctly. As for the software, the television is equipped with motion smoothing technology; however, with a key caveat – it works only for input signals up to 60 Hz. This means it is primarily suitable for traditional television, films, and series. Thanks to this, we can adjust the fluidity of the image to our own preferences – from a very smooth, "theatrical" approach to setting the slider to "zero" and maintaining a fully cinematic character.

The LG B4 television is equipped with four fully-fledged HDMI 2.1 ports with a full bandwidth of 48Gbps. All features that are identical to this standard were activated without any issues, and throughout the entire testing process, they did not cause any problems. The combination of such extensive functionality and low input lag suggests that the tested television is truly made for gaming. This is not surprising, considering that the manufacturer has always placed great emphasis on this. Therefore, we can enjoy both the properly implemented HGIG mode and gaming in Dolby Vision with low latency. This pairing will certainly attract the attention of all passionate gamers for whom quality is paramount.

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

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

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

The biggest issue 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 at all. Due to the television having a poorly implemented HGiG feature (the HDR tone mapping standard for games), it is very easy to "overexpose" the image during initial HDR calibration on the console. If someone is unaware of this software flaw and follows the on-screen instructions, they will simply set the image incorrectly, resulting in burnt-out details in the bright areas. Another major problem is the Dolby Vision mode for games. While it does work, 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 speaking, this is a really very good screen for gamers, but with one small caveat. We would rather avoid using HDR mode on it – unless we decide to manually set the brightness bar on the console "by eye", completely ignoring the instructions from the console’s pictogram.