Screen-door effect

When you watch something on a screen, like a TV or a virtual reality headset, sometimes you might see tiny little lines in between the pixels that make up the picture. It looks like you're looking through a screen door! That's why we call it the "screen-door effect."

This happens because the pixels on the screen aren't perfectly sealed off from each other - there is a teensy-weensy bit of space in between them. When you're watching something with a lot of detail, your brain can pick up on those little spaces and make it look like there are lines in the picture.

One way to imagine this is like looking through a fence. Even though the fence might have little holes in it, you can still see stuff on the other side - it's just a little harder to see because of the fence in the way. It's the same thing with the screen-door effect - the lines between the pixels make it a little more difficult to see the picture on the screen, but it's still there!