The LTDN42K320 has a maximum display resolution of 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 amongst all TVs of a similar age and spec to the LTDN42K320.
An HD Ready HD type is the worst display resolution amongst comparable types of television.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
Alternative 4K Ultra HD TVs currently available which you might also want to look at include cheaper TVs such as the 40UF7707, or the 49UF640 (£489.99) both from LG.