Cubot X18 Review

Display

Cubot X18 features a 5.7-inch IPS display with 18:9 aspect ratio and an HD+ resolution (720 x 1440 pixels). The screen has a peak brightness of 450 cd/m², 1300:1 static contrast ratio and covers 90% of the NTSC colour space. It is GFF fully laminated and protected by a 2.5D curved glass. According to the manufacturer, the screen-to-body ratio is 83%, but in reality, it is 71.22%. GFF stands for glass-to-film-to-film and refers to a style of full display lamination. These screens are thin, lightweight and cheaper to produce. Their architecture includes a two-film sensor that bonds together a PET film, ITO (the Y-axis touch electrodes), OCA (optical clear adhesive), then another PET film, ITO (the X-axis touch electrodes) and OCA. These are then topped with a protective glass.

Brightness	White luminance	Black luminance	Contrast	Color temperature
100 %	473.211 cd/m2	0.540 cd/m2	876 : 1	9585 K
75 %	367.411 cd/m2	0.417 cd/m2	881 : 1	9705 K
50 %	256.011 cd/m2	0.290 cd/m2	883 : 1	9802 K
25 %	140.325 cd/m2	0.160 cd/m2	877 : 1	9994 K
0 %	17.535 cd/m2	0.020 cd/m2	877 : 1	10413 K

The display of our review unit has a reasonable peak brightness of 473 cd/m². It is not perfect for clear outdoor viewing but is definitely better than displays with a peak brightness of 350 cd/m² and lower, which are usually used on such affordable smartphones. At the same time, the black luminance values are very high resulting in a low contrast ratio of 880:1. The temperature of the white point is high as well for the various brightness levels varies from 9500 K to 10000 K. The CIE diagram unveils an almost 100% coverage of the sRGB colour space with significant deviations in the greens, minor deviations in the reds, and an exact match in the blues areas. The display panel has a traditional striped subpixel arrangement.