Well, a lot of readers will ask; what is 4K, or as it is sometimes refered to QFHD (Quad Full High Definition)? Put simply “4K” is 4000 pixels x 2160 pixels.
So if I have a TV that is 1920×1080 (so called 1080P) now, why would I want twice that number of pixels? The answer is, unless you have a massive (and I mean >55″ screen), you don’t.
This excellent article from CNET, does the math (yes, real math) to “prove” that “…That’s right, at 10 feet, (the human) eye can’t resolve the difference between otherwise identical 1080p and 720p televisions. Extrapolating this out, you’d have to get a TV at least 77 inches diagonal before you’d start having a pixel visibility problem with 1080p…
…So if your eye can’t tell the difference between 720p and 1080p on nearly all modern televisions, what’s the need for 4K?
Excellent question. There isn’t one. Not as far as TVs go, anyway. You’d need a 2,160p TV over 154 inches diagonal before you’d be able to see the pixels. On a 4K 50-inch TV, the pixels would be roughly 0.011 inch wide.
Where’s the crossover where 1080p and 4K become noticeable? It’s not exact because of all the above mentioned variables, but suffice it to say at 10 feet, it’s somewhere well above 77 inches..”