I'm outside the Bank of England
and under that building is more than a hundred billion pounds' worth of gold.
But I'm here to talk about
significantly more sensible amounts of money specifically banknotes
If you have a look on pretty much any banknote in
pretty much many any major currency in the world, you'll find little yellow rings.
On the back of the British £10 note they are the pollen around the flower
around the flower, next to Charles Darwin.
On the US $20 bill, they are the numbers in the "20"s, in the background.
This is called the EURion constellation or at least that's that name it was given
by the German computer scientist called Markus Kuhn
who discovered it. You put this into a colour photocopier
and its image processing algorithms
will recognized this pattern. It's designed to be
really easy for computers to recognize and it will refuse to copy it.
Which means that if you want stop from copying something, put this image on it.
Of course, you can still just take a picture of it and print it out but
if you are forging bank notes with a colour photocopier
something has probably gone wrong with your life.
And that is something you may not have known.
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