Why does the permanent timestamp in CCTV footage sometimes change color?

I'm refering to this
I've also seen it happen to a single letter in that string

13 comments

it's for contrast, white text on light background is almost impossible to read same with dark on dark. Uses a per character or per pixel filter to determine the color of the text
- It seems like over engineering when stuff like this are common knowledge.
  
  Doesn’t seem like enough resolution for an outline to work.
  
  Also this conveniently doesn't show white color background.
  
  That takes up more space than they care to give it
  
  Yellow with blue line us even better for CCTV use imo.
No one gonna mention anything about how that dude is lucky to be alive? Holy shit I thought this was going to be a different kind of video.
- You think the dude in the truck is fine?
For contrast so the text remains readable.
Like others have said, for contrast.

Though, they’re not exactly “permanent.” Depending on the encoding, they’re potentially pretty easy to remove. (If it’s encoded to meta data. It’s just a playback thing. You can turn this on for VHS movies, too,)
It’s done to have a big contrast between the letter and its background, so you can read all the information all the time (except in edge cases, like the seconds in the video you show, the background is mostly 50-50 with black and white, so the text is kept in black, and can be a bit hard to read)

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