The UE48JU6445 has a maximum display resolution of 4K Ultra HD. That's over four times the display resolution of the most frequently found HD type of Full HD. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
This TV's display resolution (4K Ultra HD) is in fact the best display resolution amongst all mid-size TVs that came out around the same time as the UE48JU6445.
An HD Ready HD type is the worst display resolution across similar types of TV.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
It may also be worth also looking at one of the alternative 4K Ultra HD televisions currently available including the Samsung UE40JU6740 (£829.85), the Panasonic TX-49CXX759, or the LG 40UF671 which has a better Rating.