The highest display resolution of the Sony X800D is 4K Ultra HD. That's over four times the display resolution of a Full HD TV, which is the most frequently found display resolution. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
This television's display resolution (4K Ultra HD) is in fact the best display resolution amongst all comparable spec TVs that have been on the market for a similar time to the X800D.
Amongst similar types of television the worst display resolution is HD Ready.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.