The highest display resolution of the 54457U80 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 in fact the best display resolution across all mid-size TVs that are a similar age to the 54457U80.
The worst display resolution across comparable types of TV is HD Ready.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
Alternative 4K Ultra HD TVs currently available that you might also want to consider include because of it's better review score, the LG 49UH610 (£499.00).