Why does zooming/out/panning on an image of a CRT screen cause the screen to look ‘animated’

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I’m sure there is a better way to word that question, but that was the best that came to my mind. (Apologies in advance for not using correct terminology)

I noticed that when I’m viewing a picture taken of a CRT screen (not a screen cap, an actual picture where the CRT is one of the objects in said picture) does it appear as if the curved ‘scanlines’ of the ‘tube’ on the screen are moving as in zooming into the image.

I’ve only noticed this on my phone while looking at Reddit posts. Here is an example from the r/Dreamcast subreddit

Monday
by u/pitsloan in dreamcast

Thank you in advance

In: 0

3 Answers

Anonymous 0 Comments

That’s called a Moiré pattern. It happens whenever you slide one grid over another, in this case the grid of pixels on your phone and the rasterization grid of the CRT

Anonymous 0 Comments

That’s called a Moiré pattern. It happens whenever you slide one grid over another, in this case the grid of pixels on your phone and the rasterization grid of the CRT

Anonymous 0 Comments

That’s called a Moiré pattern. It happens whenever you slide one grid over another, in this case the grid of pixels on your phone and the rasterization grid of the CRT