Recently, I've found out that Himedia doesn't really display 4K resolution (3840 x 2160). I tested it with this
image.
First, I tested with my 4K TV's native player, and this is what it displays (It's displayed normally) :

Then I tested it with Himedia:

See the difference?
I'm not sure if Himedia upscale or downscale it, but the image is not displayed as it should be.
Using Himedia's Kodi is even worse:

The scaling is way too much.

I don't know

, now I've started using my 4K TV's native player to watch videos, although the navigation is less better than Himedia.
(And yes, I've set the Himedia's resolution to 2160p 60hz ; YCbCr420 10Bit)
I think most of 4K android boxes are only capable on streaming 4K contents, not displaying