The best factory mode in which we conducted all our tests was "Filmmaker", which is now quite standard in televisions from this manufacturer. However, let's take a look at its characteristics before we start the calibration process. The first aspect we will examine is white balance, as despite being inconspicuous, it determines whether the image will be free from any tints. The graph clearly shows that in both SDR and HDR content, two colours dominated: red and green, which caused a strong yellow tint that was pervasive throughout the image. This is perfectly visible on the "ColourChecker" palette, where all colours shifted towards their warmer counterparts. The second thing we will scrutinise are, in our opinion, the two most important graphs in the context of image quality assessment: gamma and the EOTF curve. Both are intended to maintain appropriate brightness and contrast. The first describes the level of brightness in SDR materials, while the second depicts the rate of luminance increase. Analysing the first one, we can see that it has been remarkably lowered compared to the reference value indicated by the orange line. This situation resulted primarily in a sharp increase in brightness and a significant decrease in contrast, reminiscent of what one would expect from OLED televisions. The EOTF curve showed greater "caution" and only slightly brightened the entire image to 50% of the maximum brightness.
Xiaomi, like many manufacturers, offers a wide range of picture modes. On the S MiniLED, we can find both IMAX Enhanced and Filmmaker. Our tests were conducted in Filmmaker mode, which theoretically aims to reference the image, but the reality turned out to be somewhat different.
Let’s start with the SDR material tests. Here the TV had quite a few problems, especially with white balance. The noticeable dominance of red made the image appear too warm, and all colours gained a reddish hue. This was particularly evident in the comparative scene from the film Star Wars. The brightness characteristic (gamma) also left much to be desired – instead of a smooth transition, we had a real "rollercoaster," with visible excessive brightening of the screen.
In 4K materials, the situation looked considerably better. The white balance, though still not perfect, was much more balanced, with a slight dominance of red and blue, but no excessive impact on the overall perception. The EOTF curve (responsible for brightness in HDR) showed some brightening in the brightest parts of the image, which was noticeable in the test scene from the film Pan that we described above. These brightening effects may disturb the precision of the image, but in 4K, the overall effect was far more acceptable than in SDR.
Although Xiaomi S MiniLED can pleasantly surprise in 4K materials, its factory settings in SDR require significant corrections, especially regarding white balance and brightness. It's definitely a TV that would benefit from calibration.