TCL C855 vs TCL C9K

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.

As we mentioned with black and contrast – the C9K can make a huge impression in synthetic tests. Our measurements showed that on a screen 10% filled with white, the television is capable of squeezing out… 4000 nits of brightness! It sounds astronomical, but – and here, unfortunately, the pattern repeats – the numbers say one thing, and practice says another. In real movie scenes, the situation looks different. At best, when the light effects occupy a large part of the image and the local dimming algorithm does not have to think too hard about what to do with thousands of zones – the effect is really good. At that point, the C9K can reach around 1500 nits, which provides a pleasant, intense flash and can indeed make a positive impression.

The problem starts with smaller elements – such as stars in the sky, the moon, or single reflections. That’s when the proverbial cat comes out of the bag: the algorithms are not yet refined, and brightness drops to even 400–500 nits. That’s a huge difference compared to the potential 4000 nits we saw in laboratory tests. Why does this happen? Most likely, the television is trying to protect the blacks in this way and minimize the halo effect around bright objects. Unfortunately, this comes at the cost of details – some details simply vanish, and the scene loses its nature.

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.

For color tests, as always, we reached for the Filmmaker mode – a new feature in TCL TVs for 2025. And while the direction itself is a step in the right direction, the execution leaves much to be desired. The white balance in SDR content turned out to be too warm – there was an excess of red. On the other hand, in HDR, it went in the opposite direction: the image became excessively blue. The Colour Checker test revealed quite a few color errors that were noticeable to the naked eye. An even bigger problem turned out to be what we mentioned above – brightness management. Regardless of whether we were watching SDR or HDR content, the image tended to blow out the entire scene, giving it an unnatural, even grotesque character. It's hard to call this a "director-created" mode – because the director has certainly never seen such an image.

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 calibration, we finally managed to tame the white balance – and it immediately translated into a more natural image. Colors finally started to look the way they should, and the overall presentation was incomparably better than in the factory settings. In other words – it’s worth taking a moment to improve this, as the gain is truly significant. The gamma responsible for managing brightness was also brought into order in SDR content, and the effect was more than satisfying. Unfortunately, when we turned on HDR materials, the situation quickly became complicated. No matter how we set the local dimming, the television had a tendency to do what it liked with the image – either it overexposed everything or dimmed the darkest parts too much. Exactly as we saw in the scene from the movie Billy Lynn. So, the color improvement after calibration makes a great impression, but brightness management in HDR remains the Achilles' heel of C9K and presents a certain technological limitation.

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.

Digital image processing in TCL C9K is quite mediocre. The tonal smoothing feature seems to be present, but turning it on practically changes nothing – color bands are still visible, and it can unintentionally highlight elements we would prefer to hide, such as textures of objects. Fortunately, it doesn’t remove film grain, but that’s small comfort since the effects are still poor. Therefore, it's hard to recommend using this option.

On the other hand, image scaling performs much better. Lower quality materials look quite decent – characters and backgrounds are presented clearly, although, of course, with sources at 576p, physics cannot be fooled. Sometimes, characteristic aliasing on objects appears, but that’s the fault of the source itself, not the algorithm. A plus for not having issues with overscan – the image is not artificially cropped or enlarged.

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.

Like the C8K, the C9K is also a really fast television – both figuratively and literally. It features a 4K panel with a refresh rate of 144 Hz, and at lower resolutions, the display can even ramp up to 288 Hz. This speed translates into practice – when watching sports or playing games, the image looks very smooth and clear. Additionally, in films, we get an extra motion smoother called Motion Clarity, which allows us to adjust the fluidity to our own preferences – from the cinematic "judder" frame to almost theatrical smoothness.

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.

For gaming, the TCL C9K is a complete tool. Here we have two (out of four) HDMI 2.1 ports with full bandwidth of 48 Gbps, so all key technologies work: VRR (variable refresh rate) and ALLM (automatic low latency mode). Additionally, the manufacturer added a really intuitive Game Bar, which allows you to quickly preview the most important parameters and adjust settings without digging through the menu. Also, TCL's policy is a plus – the TV is not afraid of any HDR formats, even in game mode. Whether it's HGiG or Dolby Vision for the Xbox Series S/X console – everything works as it should, giving the player wide freedom.