The VIZIO D50u-D1 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 mid-size TVs that have been on the market for a comparable time to the D50u-D1.
An HD Ready HD type is the worst display resolution across comparable types of television.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.