A recent study conducted by researchers at the University of Cambridge and Meta Reality Labs has pinpointed a definitive “resolution limit” for the human eye. This finding suggests that increasing pixel density in TV displays beyond this limit provides no tangible benefit to the viewer. The research, published in *Nature Communications*, focused on measuring what viewers can actually perceive on modern screens using pixels-per-degree (PPD) – which is the number of pixels within a single degree of the viewer's field of vision – instead of relying solely on headline screen resolutions.
Volunteers were shown detailed greyscale and colour patterns while the screen's distance was adjusted. Measurements were taken for both central and peripheral vision. The results showed higher limits than the commonly cited 20/20 vision rule of 60 PPD. Notably, there were differences between greyscale and colour: around 94 PPD for greyscale when viewed directly, 89 PPD for red/green patterns, and 53 PPD for yellow/violet. The study indicates that because colour perception diminishes more rapidly, especially in peripheral vision, increasing pixels doesn't always equate to a sharper perceived image.
For consumers considering a new TV, the researchers emphasize that the advantages of 4K or 8K depend on both viewing distance and screen size. According to the study, in a typical UK household with a viewing distance of approximately 2.5 metres, a 44-inch 4K or 8K TV offers no noticeable advantage over a Quad HD (QHD) display of the same size. Increasing pixel density beyond what the eye can discern increases panel cost, power consumption, and processing demands without enhancing perceived detail. The group has even created an online calculator allowing consumers and manufacturers to determine when a specific screen reaches “retinal” resolution based on room size, viewing distance, and display specifications.
The research findings have implications beyond televisions, extending to mobile devices, AR/VR headsets, automotive displays, and content delivery. Understanding the upper limit of perceived detail can inform display development and allow streaming and gaming services to optimize rendering and video coding. "The authors argue that as industry effort goes into ever-higher pixel densities, understanding what viewers actually see provides a clearer “north star” for future display and imaging technologies." Knowing what viewers actually see provides a clearer “north star” for future display and imaging technologies.