TCL C75B offers various picture modes, but in our opinion, the best choice is the “Film” mode. Although its settings are quite decent, the TV struggles with certain colour reproduction issues. In tests, we noticed that the image had a noticeably pinkish hue compared to what could be considered correct. This effect was particularly evident in skin tones, which appeared unnaturally flushed. The main culprit of this phenomenon turned out to be the white balance, characterised by an excess of blue and red in both HD and 4K HDR materials.
An additional problem was the way brightness was reproduced. The gamma, which is responsible for the visibility of details in darker materials, was definitely boosted, causing details in the darkest parts of the screen to be invisible, disappearing into complete black (e.g., the bottom part of the screen in the comparison image - the area around the actress's ear). The situation was similar on the EOTF curve, which was below the correct value, suggesting that a similar issue may be encountered in 4K HDR content.
Thanks to our experience and the appropriate tools, we decided to take matters into our own hands and check how much could be extracted from this model after professional calibration. The details are described in the next section.
Every reliable assessment of image quality must start with selecting the most optimal, factory preset mode. In the case of the tested P7K/P79K model, the choice was made without hesitation for the "Film" mode. It is the mode that presents an image closest to the intentions of its creators, avoiding both the exaggerated brightness of the 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 without a few stumbles. The most noticeable shortcoming turned out to be the not entirely correctly set white balance. A slight dominance of the blue component gives the image a subtly cool, frosty character, straying from the ideal neutrality that the director intended to show us. The television handles the reproduction of greyscale in the standard dynamic range much better – the gamma curve is almost exemplary. The only slight reservation can be made for the darkest parts of the image, where a delicate deviation from the norm causes a loss of some detail in the shadows. The most significant challenge, however, for the TCL software was interpreting the HDR signal, as 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 mid-tones. Fortunately, most of these imperfections are of a software nature, which can be eliminated. With that thought in mind, we proceeded to the process of professional calibration.