Can the Human Eye See 8K Resolution and When is 8K Most Useful?
June 29, 2021 - Erikka Innes
4K has been around just long enough for some of us want the next best thing and when it comes to resolution, we may be approaching our limit. That might sound strange at first, if you've heard about Roger Clark's project to find out how many megapixels the human eye can see. By his calculations, you can see up to 576 megapixels. 8K only creates 33.17 megapixel images, so what gives? We should be able to see a lot more.
The answer in the way the human eye processes visual information. The way it's designed, you can only see with the kind of clarity required for a 576 megapixel image with a tiny part of your eye called the fovea. It lies at the center of your visual field and covers about 1% of the retina. Amazingly, about 50% of the part of your brain that's for visual processing focuses solely on details received from the fovea! What is more, in the very best of lighting conditions for your eye, with someone with the very best vision, that person can only see about 1/60th of a degree with their fovea. This is the equivalent of a dot .07 inches across and 20 feet away!
To get a clear picture of what's around you, you move your eyes (and therefore the fovea) around in staccato, involuntary twitches called saccades. You use these plus voluntary eye movement to collect information with the fovea while your brain fills in gaps for what you aren't looking at directly in that moment. That's right - your eye and brain create their own lossy compression algorithm! Most of the time you are faking information, and using your fovea to focus on something before moving on to the next thing. Translated into pixels, the fovea is collecting about 5-7 megapixels in an image.
Okay, So Can We See 8K?
If that's how we see, can our eyes detect 8K? Do we need 8K if it's just a tiny part of your eyeball that can really see with the incredible level of detail you'd need to enjoy 8K in an image? The answer is...it depends. If you're going to sit at home on the sofa and stare at a TV, then no, probably not. According to Paul Maguire, you'd have to sit less than 4.2 feet away from your 65 inch TV or 3.6 feet away from your 55 inch TV to see all the detail in 4K. For anything greater than 4K you'd have to sit less than 3 feet away. Which is liable to irritate any other viewers in the room that wanted to see the screen around you. This doesn't mean 8K resolution isn't useful.
Benefits of 8K
8K is potentially beneficial for recording video. If you have 8K quality, you can zoom in on parts of your shots and still have 4K quality or better. It can allow someone shooting to have more choices from every shot because the quality will still be very high.
8K is also great creating intensely realistic, immersive experiences. If you have a wrap around TV or a planetarium, or virtual reality goggles, 8K is amazing. It allows for the rendering of softer, more realistic edges. It increases the realness of a scene because the human eye can't see any pixelation. So for virtual reality, 8K will probably become the standard. As for becoming the standard for streaming video, probably not for awhile. It's not necessary in many cases, and at this time it's also difficult to stream at that level and know it will arrive at its destination as 8K. Someone streaming in 8K would likely end up outputting to lower resolutions based on the wide range of viewing devices users have.