Going to any institution which deals with currency; its collection and distribution like a bank is a good idea to get a general picture on which hidden pictures are used to protect the national currency from being reproduced. There are always pictures found on the walls in areas like a bank so that those people who pass by on a regular basis can take a look and learn how to spot counterfeit currency if ever faced by the situation which requires checking.
The issue with having counterfeit currency is that it is hard to trace back to the maker and virtually impossible to use when you have received it from someone else, which is why knowing everything on which methods are used to make money safer will allow you ease of mind.
Holding a currency note against light will allow you to see which hidden pictures there are. Usually, there located on the left side of the note and on the right side when you turn it around. This rule is not a universal one and can be different depending on the currency being used. Most of the time, hidden pictures will be of national symbols like a maple leaf in Canada, or the Queen.
Special Currency Detection Lights
Special UV lights which are most commonly found being used by cashiers is another sure method of seeing hidden pictures on money. This method may not be one that you have access to, but such devices are easily available in the market and guarantee to allow you to see the hidden trademarks of such notes when necessary. These devices come especially in hand when you are dealing with larger notes, since they are most likely to be counterfeited than smaller ones.