TCL C855 vs TCL P7K / P79K

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.

When evaluating the HDR effect, we must make it clear and without marketing embellishment: the P7K/P79K is not and was never meant to be a master in this field. The maximum peak brightness that this panel can generate is only around 300 nits. This is a borderline value, a sort of thin red line between what can be considered a barely satisfactory HDR signal and what is really not much different from standard dynamic range (SDR), unfortunately leaning towards the latter. Synthetic tests found brutal confirmation in reality – our measurements taken during movie screenings showed that luminance in key bright parts of the content rarely exceeded the threshold of 200-250 nits. Therefore, this is not a television that would allow content produced in a wide tonal range to truly shine, and we must openly acknowledge that.

Unfortunately, the issue of color reproduction is presented equally restrained. Although the manufacturer positions this model in the "QLED" family, thanks to the use of a PFS LED filter, the results do not match the heightened expectations. The coverage of the wide DCI-P3 color gamut is only 86%. Compared to the market, this is at best an average result, as most devices that employ additional layers to expand the color spectrum easily achieve values at a minimum level of 90-92%.

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.

Every reliable image quality assessment must begin by selecting the most optimal factory mode. In the case of the tested model P7K/P79K, the choice was confidently made for the "Film" mode. It is this mode that presents an image closest to the creators' intentions, avoiding both the exaggerated brightness of dynamic mode and the excessive dimming known from eco settings. And it must be admitted that, for a device in this price range, the factory calibration is surprisingly decent, although it is not free from a few stumbles. The most noticeable flaw turned out to be an imperfectly adjusted white balance. A slight dominance of the blue component gives the image a subtly cool, chilly character, thus deviating from the exemplary neutrality that the director wanted to show us. The television performs much better in reproducing the grayscale in a standard dynamic range – the gamma curve is executed almost perfectly. A minor reservation can only be made for the darkest parts of the image, where a slight deviation from the norm causes a loss of some detail in the shadows. The most serious challenge for TCL's software, however, was the interpretation of the HDR signal, which is illustrated by the EOTF curve. The television follows its own, rather free path here – the darkest details are disproportionately brightened, followed by a noticeable slowdown in brightness increase for midtones. Fortunately, most of these imperfections are software-related issues that can be eliminated. With this thought in mind, we proceeded to the professional calibration process.

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.

The calibration process turned out to be a home run, especially in the context of standard dynamic range (SDR) content. We successfully managed to eliminate the TV's tendency to emphasize cool tones, restoring the whites to their natural neutrality. Furthermore, precise adjustments allowed us to correct a slight error in the gamma curve, so the darkest areas of the image regained their proper depth, without a trace of unnatural brightening. The effects are measurable and impressive – in the ColorChecker test, the vast majority of color reproduction errors fell below the perceptual threshold, achieving a deltaE value below 2. This is a result that would not shame much more expensive constructions. Unfortunately, in the case of HDR content, we hit a wall in the form of the inherent limitations of the panel itself. And although we managed to bring the colors in line, the software's specifics mean that the TV still adapts brightness in its own way, as evidenced by the persistent, non-standard EOTF curve. In summary, calibration brings tremendous added value, but one must be aware that it cannot overcome certain physical barriers. A slight boost in black levels, resulting from the lack of local dimming, and limited peak brightness mean that HDR content will not always be able to showcase its full potential. This is simply not the main task of this display; its true strength, especially after professional tuning, lies in the viewing of SDR materials.

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.

After a series of harsh evaluations, fortunately, the time comes for praise, and this is due to the TCL AiPQ image processor for its work in digital processing and content scaling. It should be noted right away that we are not talking about the level known from flagship designs; nevertheless, in the price segment represented by the P7K/P79K, the results achieved are more than solid. The feature that smooths tonal transitions performs particularly well, effectively eliminating posterization, which are the characteristic bands often visible in materials with higher compression, such as from the YouTube service. The algorithm can elegantly remove unwanted gradients, which ultimately looks really good. The television also competently handles upscaling, which is the task of raising low-resolution materials to 4K standard. The output image, although it may seem a bit too sharp out of the box, fortunately, is not a problem. The software allows for easy adjustment of this parameter using a sharpness slider, so the final appearance can be easily tailored to personal preferences.

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 issue of fluidity and sharpness of the image in motion is inextricably linked to the fundamental parameter of the panel, and in the case of the TCL P7K/P79K, we are dealing with a panel that has a native refresh rate of 60 Hz. This specification already defines its capabilities and makes it difficult to unequivocally recommend it to enthusiasts of dynamic sports broadcasts. During rapid camera movements, the image loses sharpness, and the panel itself also shows a slight tendency to blur, which may be noticeable to more sensitive viewers. Fortunately, not everything in this aspect has been left to chance. The manufacturer has implemented a simple motion smoothing system, which is primarily used in film materials recorded at 24 or 30 frames per second. Thanks to a dedicated slider, the user can independently decide on the final character of the motion – from a fully cinematic, slightly juddery image to achieving a very smooth, almost theatrical effect. It is a simple yet effective tool that allows users to tailor the viewing experience to their own preferences.

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.

Although on paper the native 4K@60Hz matrix might suggest that the TCL P7K/P79K is not a TV tailored for gamers, the reality turns out to be surprisingly different. On the contrary, the manufacturer has ensured a rich package of features that make it a very friendly companion for next-generation consoles. Onboard, we find key technologies such as ALLM, which provides automatic switching to low-latency mode, and VRR, or variable refresh rate, which eliminates screen tearing. The list is completed by support for Dolby Vision Gaming and a simple yet functional Game Bar. However, the real and extremely pleasant surprise is something else. It turns out that the TV easily supports high refresh rate signals of 120 Hz, but at lower resolutions – 1080p and 1440p. This is fantastic news for console owners who know full well how rarely games run in native 4K at a full 120 frames per second. The ability to choose between higher resolution and doubled smoothness is therefore an extremely sensible compromise.

In summary, although the P7K/P79K may not be the target screen for the most avid tournament gamers, it offers a package of options for the casual or occasional console user that is hard to find among many competitors at this price point.