Mystery #4Tier 3holograms and light

How does a flat shiny sticker hold a picture that looks solid and 3D?

Tilt the shiny sticker on a bank note or a credit card and a little picture seems to lift off the surface, turning and glinting as if it were really there. But the sticker is flat as paper. How does a flat shiny sticker hold a picture that looks solid and 3D?

A close-up of the hologram patch on a fifty euro banknote, shimmering in green, blue and gold — Photo: Heike Löchel · CC BY-SA 3.0 · via Wikimedia Commons

Your guess

What do you think the flat sticker is secretly keeping a copy of?

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