WEBVTT
Kind: captions
Language: en

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I'm outside the Bank of England

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and under that building is more than a
hundred billion pounds' worth of gold.

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But I'm here to talk about

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significantly more sensible amounts of money
specifically banknotes

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If you have a look on pretty much any banknote in

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pretty much many any major currency in the
world, you'll find little yellow rings.

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On the back of the British £10 note they are the pollen around the flower

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around the flower, next to Charles Darwin.

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On the US $20 bill, they are the numbers
in the "20"s, in the background.

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This is called the EURion constellation or at least that's that name it was given

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by the German computer scientist called Markus Kuhn

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who discovered it. You put this into a colour photocopier

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and its image processing algorithms

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will recognized this pattern. It's designed to be

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really easy for computers to recognize and it will refuse to copy it.

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Which means that if you want stop from
copying something, put this image on it.

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Of course,  you can still just take a picture of it
and print it out but

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if you are forging bank notes with a colour photocopier

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something has probably gone wrong with your life.

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And that is something you may not have known.

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