The latest and greatest thing in TVs are new models with 8K resolution. That’s 7680x4320 pixels or four times as many pixels as a 4K TV and 16 times as many as a 1080p TV. Do these new 8K TVs offer a differentiated experience? Can you see the difference?
If simple visual acuity does not full describe our ability to “see” resolution, what are the mechanisms? There appear to be two other factors at play: Vernier acuity and the brain. Vernier or hyperacuity refers to the ability to discern slight misalignments between lines – an ability that is not possible according to simple acuity descriptions of human vision. Hyperacuity means we can perceive fine details even at fairly long viewing distances.
A classic way to prove this is to show to two line-pairs. One pair has two black lines on a light background with the two lines perfectly parallel. The second pair can be misaligned by just a single pixel and many people can see this – even at some distance away. Because modern displays are pixelated, a line that is not parallel will have stair-stepping. While our normal visual acuity may not see this, our Vernier acuity can. As a result, if 4K and 8K images are displayed on 4K and 8K displays of the same size and viewed at the same distance – all other factors being equal - the 8K image will look sharper or crisper vs. a 4K image even when viewed at 8-10 feet. That’s because the spacing of the pixels on the 8K TV is half that on the 4K TV so there will be reduced stair-stepping – i.e. the 8K display will create a smoother line compared to the 4K display in this example.
It would also appear that the brain does processing on the data sent from the eyes. In the above example, the reduced stair-stepping is reinforced in the brain to create a more analog-like image and hence an increase in the “realness” of the image. Given a high-resolution input to the eyes, the brain does a good job of filling in any missing details (and must work less hard compared to lower resolution inputs). This processing also creates an increased sense of depth.