ELI5: What is the static we see if we focus our eyes hard enough?

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Why is it that I have seen animated images within that static? They used to be more vivid when I was a kid.

caucasoidape

Are they such tiny dots that you aren’t even close to be able to focus on an individual dot? And they fill every part of your vision. I wanna say they are all different colors, maybe? But not really sure. If so, I’m also curious to what it is I’m seeing.

Joe30174

Imagine you had the most sensitive eyes in the world, that could tell a billion slight shades of light and color apart. Even with such excellent eyes, if a bit of light fell between 2 of the values your eye could detect, your eye would not see the actual value, it would see it jumping back and forth rapidly between the two closest values. Basically there would be noise due to the imperfect conversion of photons to electrical impulses. What your eyes actually see is even worse than a shimmering static filled image though. You have floaters in your eye juices, bits of protein that float around clouding your vision. Sometimes you see them as little soap bubbles in your vision, usually when staring at a bright, undetailed background like the sky or a white monitor. You try to look at them but they move with your eyes because they are inside your eyes, moving your eye moves the floaters. It’s even worse than that though, you don’t have a continuous field of vision. There are blank spots in it where you can’t see nearly as well, or even see anything at all. Big old holes in your vision. All of your detail is in the center of your vision, with things becoming progressively more blocky and blurry the further out from the center of your gaze. And yet you don’t see these holes, these gaps, and you aren’t aware of your vision blurring away from a sharp center. This is because your mind has built in noise cancellation, error correction, and hole mitigation. It literally takes the raw image of your eyes, photo shops away the holes and gaps in your vision (where your optic nerves attach to the back of your eyes, or if you’re unluck, where the glaucoma is attacking your vision) and it fills in the holes with what it thinks you would see. So you aren’t aware of these gaps. The mind reduces the noise you’re aware of and it becomes very hard to see unless looking at very artificial conditions like white screens on a monitor, a pure blue sky, Very low light where even the brains noise cancellation can’t keep up with the lack of photons hitting your eyes. Your eyes are also constantly scanning around looking back and forth, and your brain uses the detail they gather in these darting movements to artificially make up for the fact they only see sharply in a very narrow cone in the middle. By rapidly looking around, darting your eyes, your brain takes the slices of high resolution vision and stitches them together into a fake, high resolution view of your world. If your eye is the CMOS sensor or CCD of a digital camera, your brain is the image processor that de-noises it, color corrects, and makes the images look good. Your awareness of this visual processing changes with light, with attention, with health, with medications, with age.

kodack10

Fun fact if you almost close your eyes the blurry or rippling effects you see are due to defraction and constructive/destructive interference of light rays. It works with any thin slit or hole.

JeffreySystem

You sometimes can see the shadows of cells, blood cells etc… being projected onto your cornea. Looks like amoebas floating around.

FreQRiDeR