The highest display resolution of the 49UF6400 is 4K Ultra HD. That's over four times the display resolution of the most common HD type of Full HD. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
A 4K Ultra HD HD type is actually the best display resolution across all mid-size TVs that have been available for a similar time to the 49UF6400.
Across similar types of TV the worst display resolution is HD Ready.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.