There are 5 circles, all of a dif'rent colour - I don't know which one's suppose ta give a hint. Thought it was the black one - but ... it's black! - Where's the hint?
Well!
The other pictures seemed to be too easy! So I'm trying to make it less easy..
Actually, all 5 circles are part of the hidden picture!
I should have said that, though. Sorry.
j. U. d. E.