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.
Alright, how does the television handle colours straight out of the box, without any intervention from our side? The Haier K85F offers a whole range of picture modes, such as Dynamic or Eco, but for anyone wanting to watch films according to the creators' intentions, there's essentially only one that matters: Film mode. This is where we focused our tests, and unfortunately, its name has little to do with reality. The picture on factory settings is very far from what we could call cinematic fidelity and requires many adjustments. Let's start with the white balance, which has a clear deficiency of red colour. In practice, this means the entire image has a cool, bluish tint. Even worse is the issue of brightness management, that is, the gamma curves (for SDR) and EOTF (for HDR). Their graph resembles a true rollercoaster, which terribly impacts the viewing experience. This results in unnatural dimming of SDR content, causing details in the shadows to be lost, and in the case of HDR – an excessive brightening that further exacerbates the problem of clipping. Such a combination, which consists of too cool white combined with chaotic brightness and too much blue colour saturation, leads to enormous errors in colour reproduction. Our measurements on a specialist ColourChecker chart showed errors (Delta E) regularly reaching and exceeding values of 8-9. To put it simply: errors above the threshold of 3 are easily noticeable to the naked eye, so such a result means that the colours on the screen are simply heavily distorted.