TCL C855 vs LG OLED G6 (G64LW, G66LS)

The TCL C855 delivers a highly varied HDR effect. At times, the television truly excels, while at other moments, it appears reminiscent of a low-end model equipped with FALD backlighting. Inconsistency is frequently found with this brand, so it didn’t come as a surprise. The first and last scenes, which feature large light elements, are nothing short of spectacular, boasting brightness levels of 1470 and 1820 nits, respectively. Such brightness can make viewers squint their eyes, allowing them to feel the extraordinary dynamism of the scene. It genuinely immerses the audience, creating a sensation of being inside the movie itself. However, the situation shifts dramatically when small or subtle elements with high luminance appear against a dark background. In these instances, the TCL C855 significantly reduces brightness to levels as low as 240 nits to mitigate halo effects. This reduction is disappointing, as it can make the movie appear as if it was not filmed in HDR. Despite these shortcomings, the HDR effect on the TCL C855 enhances the viewing experience during dynamic scenes, making it feel more engaging and allowing the viewer to feel part of the action. Even with smaller high-luminance elements, the television retains details without excessive dimming. Additionally, the TCL C855 adjusts image brightness according to scenes with rich detail, further enhancing viewing comfort.

The LG G6 is currently one of the brightest OLEDs on the market. Its peak brightness reaches nearly 2500 nits, and best of all – this has a direct impact on real film scenes. The television flawlessly pulls out details in the bright parts of the image. And this is regardless of whether we are talking about very small points like stars in the sky or slightly larger elements on the screen. Naturally, with full-screen, uniformly white scenes, the brightness of the G6 decreases due to the panel's protection system (ABL). However, in real, varied film shots, this value still hovers around 2000 nits, which can be considered an outstanding result. The coverage of the color palette also deserves praise. The new 2nd generation Tandem OLED panel brought only a cosmetic change, but still an improvement. The DCI-P3 color gamut coverage reaches nearly 99.5%, while the ultra-wide BT.2020 is around 84%. These are very good results, although one must remember one thing: at extremely high brightness levels, the volume of colors will be lower than in QD-OLED panels from Samsung Display due to the use of a white sub-pixel (WOLED). However, in everyday content and most films, detecting this difference will be very difficult.

The best factory mode for the TCL C855 is the "Film" setting, and all our tests were conducted using this mode. However, like many predefined modes, it has flaws that should be addressed to achieve an image closer to the producer's original vision. In our examination of the colour characteristics for both SDR and HDR materials, issues were found.

Focusing first on SDR content, there is a noticeable dominance of green in the white balance, which leads to an unpleasant greenish tint across the entire image. The gamma chart, crucial for image contrast, shows a significant deviation from the reference line marked at 2.4. Initially, there is a pronounced spike in the measured value, resulting in an over-contrasted image where details can merge into a dark blob. This condition persists for nearly 20% of the chart before it dips below the reference line, causing the image to brighten and resulting in a substantial drop in contrast.

In HDR materials, the factory mode performs somewhat better; the white balance appears more balanced overall, although the green tint resurfaces in the latter half of the spectrum. When we look at the Electro-Optical Transfer Function (EOTF) curve—unlike gamma, which reflects contrast—we identify two main errors: the darkest scenes are too dark, while the brightest ones become overexposed. This discrepancy was evident in our review of the scene from the movie "Pan," further illustrating the TCL C855's HDR performance issues.

We tested the LG G6 in the best factory mode for color fidelity, which is FILMMAKER MODE. For our test unit, this mode was fairly well-tuned right out of the box. In SDR content, the only thing we could nitpick was the white balance, which leaned towards warmer tones. As a result, the image could sometimes appear slightly yellowed; however, overall, it wasn't a bothersome issue. The G6 performed a bit worse with HDR content. There, we noticed too much blue component in the white balance. This caused the image to take on cooler shades, resulting in quite noticeable errors. As can be seen in our ColorChecker chart, colors were indeed shifting towards these cooler registers. Nevertheless, for factory settings, the television displayed a completely decent level. However, we know that OLED screens – especially those from LG – respond wonderfully to professional calibration, which is why we immediately proceeded with it.

TCL, like most manufacturers, offers advanced calibration tools within its televisions. These include both 2-point and 20-point adjustments for grayscale, as well as a comprehensive colour management system. As a result, we achieved impressive results in SDR materials, bringing the image significantly closer to the reference standard. We successfully eliminated both the green tint and the gamma issue, although a slight "kink" at the very beginning of the gamma curve still persists.

In contrast, the situation with HDR materials was less favourable, as the TCL C855 did not allow for precise modelling. We were only able to make minor adjustments to the EOTF curve while significantly enhancing the overall colour accuracy. This limitation suggests that while calibration tools are effective, they may require further refinement for optimal HDR performance.

After conducting a professional calibration, we gained complete control over the panel, and we were able to adjust all parameters to nearly zero. We managed to perfectly tune the white balance, which made the factory-cool and warm tints disappear from the screen. The effects are clearly evident in the ColorChecker test – the average color reproduction errors dropped below the critical value of 1-2. And what does that mean? PERFECT colors, with no distortion whatsoever! However, from a reviewer's obligation, we must comment on how the LG G6 autonomously manipulates brightness, for which the EOTF curve is responsible. When we look at the standard synthetic graph, it may seem that the line is quite straight. The situation changes, however, when we turn on the measurement filter, which shows how the television interprets brightness in real, moving film scenes (EOTF in MOVIES). At that point, it becomes clear that some of the smallest fragments on the screen are slightly over-brightened by the algorithm. Of course, for the average viewer, such a deviation will be practically unnoticeable, but in the test of such an expensive screen, it is worth noting – especially since we are talking about a model that has huge aspirations to be the best television of the year.

Once again, we will take a look at the function of smoothing tonal transitions, but this time also image scaling. The latter is particularly important when watching materials of lower quality, such as some television programs or older films. We will focus on the function responsible for tonal transitions. Interestingly, just like in the scenes from the previous test where it performed excellently and smoothed out practically all the inconsistencies, here it had issues. Using the menu responsible for the operation of this function, we found that no setting—even the strongest—was helpful.

Image scaling in TCL C855 is defined as one of the best we have had the opportunity to test so far. The image is sharp, but in a way that could be described as natural to our eye. Even small, fine branches do not have jagged edges, and there is no white halo around figures, a characteristic of weaker scaling systems.

No matter what one may say about the G6's problems with near-black signal, it must be fairly acknowledged that it handles highly compressed material and lower resolution content brilliantly. All unwanted, ugly tonal transitions are effectively reduced here by the “Smooth Gradation” feature. On the “Low” setting, the algorithm operates flawlessly – effectively masking the artifacts resulting from strong compression, without destroying the sharpness and details in the frame. Higher levels of this feature indeed smooth the image even more, but they start to blur the real texture elements of objects, which is why we recommend keeping this slider at a low level. As for the upscaling to 4K, the processor does an excellent job – edge sharpness and detail reconstruction are at the highest level, and in this respect, the G6 does not lag behind the world's best.

The maximum refresh rate you can set on the TCL C855 is 144 Hz. Naturally, this is only possible after connecting the TCL C855 TV to a very powerful PC. Otherwise, we will be operating at a maximum refresh rate of 120 Hz, which is recommended if we want to watch primarily sports or materials with a lot of motion dynamics. For those who require high image fluidity, the manufacturer has implemented a multi-stage motion smoother. It is divided into two separate sliders which control the sharpness of moving images (Motion Blur Reduction) and flicker (Flicker Reduction). Both sliders can be adjusted from 0 to 10, with each level affecting the degree of fluidity, so everyone can find their sweet spot. We present a setting that allows for slight smoothing without the soap opera effect. The matrix of the TCL C855 features a very good response time. This is particularly important since VA panels often struggle with the so-called ghosting effect, where a black halo can be observed behind a fast-moving object. where a black halo can be observed behind a fast-moving object.

The LG G6 is an OLED television, so in the category of motion fluidity, it traditionally deserves the highest ratings. The television supports a very high refresh rate of up to 165 Hz in 4K resolution, but most importantly – you will not see any signs of blurring on the screen. The response time of the panel is incredibly fast, ensuring that dynamic images remain perfectly sharp.

The TCL C855 TV has fully-featured HDMI 2.1 ports, boasting a full bandwidth of 48 Gb/s. During our testing, we confirmed the seamless operation of all functions included in this connection standard. As highlighted, all checkboxes are illuminated in green, a feature that will undoubtedly be appreciated by gamers, whether on consoles or those using the TV as a computer monitor. Additionally, the TCL C855 supports both AMD FreeSync and NVIDIA's G-Sync, which can be easily activated in the graphics card settings. Those with powerful configurations can feed a 144 Hz signal to the C855, which handles this effortlessly. It is also worth noting the implementation of the HGIG mode, which can be excessively bright due to the shortcomings of the "Game" mode, making proper configuration on the screen challenging. Fortunately, the TV excels with the Dolby Vision format.

TCL, as one of the pioneering manufacturers, has equipped its televisions with a special GameBar, allowing for extensive adjustment of settings "on the fly" without the need to exit the game. This feature includes options like an additional crosshair grid, black level correction, and settings designed for individuals with disabilities. The image showcases the next generation of this solution.

In summary, the TCL C855 TV is an ideal choice for those seeking a screen for all forms of electronic gaming. With comprehensive features supporting such entertainment, it provides an extremely engaging experience. It is also important to emphasise that it maintains very low input lag, regardless of the selected settings, including when using the Dolby Vision HDR format.

LG G6 is a true monster for gamers and one of the best-equipped TVs in this regard on the market. The manufacturer did not seek compromises and equipped this model with as many as four full HDMI 2.1 ports with a maximum bandwidth of 48 Gbps. This means that no matter which port you plug your PlayStation 5, Xbox Series X, or powerful PC into, you will extract the absolute maximum from them.

The TV supports a full suite of gaming technologies: from VRR (Variable Refresh Rate), through AMD FreeSync Premium Pro, to Nvidia G-Sync Compatible. Let's add to this the remarkably low, almost imperceptible input lag and a brilliantly functioning gamer panel (Game Optimizer), which allows you to continuously monitor the signal parameters. Gaming on this screen, with the perfect black of OLED and powerful refresh rates, is pure pleasure.