The Xiaomi Mi Note 3 camera performed better than the much more expensive iPhone 7 Plus or Sony Xperia XZ Premium in the DxO Mark test.

Before its release, it was already foreseeable that it would break away from the OLED panel of its predecessor Mi Note 2 edge, and the Mi Note 3 is much more restrained in terms of performance. The Mi Note 3 is selling well in its home country, and a cheaper version with 4GB RAM has already been released. However, it has not been an undivided success in our country and the price is still unreasonably high. And the lack of support for the 800 MHz LTE frequency hasn't helped sales either. But now the Focus on the Note 3's camera. After the launch of the Mi 6, it was already clear that Xiaomi had stepped up its game this year, and managed to create a significantly better system than the camera of last year's poorly performing Mi 5s Plus. The same unit was built into the Mi Note 3, which was well tested by DxO Labs.
The validity of the tests has been repeatedly questioned by journalists. In several high-end devices, we have found "paid-for results", i.e. surprisingly good results for some manufacturers' products that have fallen short of the expected quality in other tests. However, the current Top 12 list can be considered fair, as the players performed similarly in other tests.
The Xiaomi Mi Note 3 is not a high-end device. Nor was it advertised as such at its launch, unlike its camera. The dual camera system was rightly called the "flagship camera", because it is.
The Mi Note 3 scored 90 out of a maximum of 100 points, tying it with last year's Google benchmark, the Google Pixel. Google is known to be strong at perfecting the processing algorithm, which is why both last year's and this year's top device came in at the top of the podium. The Mi Note 3 beat big names such as this year's Sony Falgship, the Xperia XZ Premium, and Apple's 2016 model, the iPhone 7 Plus. Without exception, the list includes a top handset from the same manufacturer, even Xiaomi's phone is a mid-range smartphone.

The Mi Note 3 scored 94 points in the DxOMark photo benchmark and 82 points in the video benchmark. DxOMark's test proves that the Mi Note 3's camera is fast, with accurate autofocus and impressive zoom capabilities (thanks to the 2x optical zoom).
It can shoot in a variety of lighting conditions with effective noise reduction. Stunning bokeh effects can be achieved thanks to the software's two different lenses with different angles of view. However, fine detail is lost in low light. Noticeable noise can also be detected in homogeneous areas, as well as in high contrast shadows and highlights. Some colour reproduction inaccuracies are also observed compared to the reference.

The Apple iPhone 8, Google Pixel and HTC U11 scored 93, 90 and 90 respectively in DxOMark's photo measurements. However, before the Mi Note 3 test, these phones scored an impressive 94. The low score of 82 for video capture baseline was reduced from 90. The Mi Note 3 is thus among the top 10 camera phones at the time of writing. Congratulations.
The full test read in original language here.