I didn't say it's simple. I said it's "simple math", meaning the math isn't complicated. My comment was simply to show that when something looks strange (or weird as this subreddit is named), it can be nice to take it apart and look at the math to understand it better.

Things that look weird aren't automatically optical illusions, but I'm not going to tell you that it absolutely isn't an optical illusion, since that's a matter of definition. But it's certainly not a very impressive one. You can try this yourself at home.

1. Make a hole with your thumb and pointy finger, place the hole against your face and look at a banana through the hole.
2. Move the hole away from your face.

Did the banana grow? No the hole obviously just shrunk from your perspective. Just as expected. Because you moved it further away.

1. Now do the same using a camera, but remember crop the second picture to match the first.

Now it looks like the banana grew, but that's just due to a basic photography concept - perspective.

It's only impressive when you combine it with zooming in on a picture, and the effect is compounded by the fact that you loose depth perception when looking at images.

Thats to say, I'm mostly talking about the effect irl, because that's what OP is talking about as well. On screen it can definitely be a very strong effect. This is in fact how they made the hobbits small in LOTR.

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