Here's an example from real life (in person, not via this app).
I have a buddy who is blind. In the US, paper currency is all the same size and shape, so it's impossible to distinguish them by feel alone. He uses a system of folds to remember which bill is which, but if he drops one, or the cashier doesn't tell him what the denominations are, etc..., he ends up not know which bill is which. Occasionally that means he has to ask someone, despite having a 'routine' that is generally very effective.
This iOS currency recognition app is accurate and easy to use. If only more visual recognition apps were this easy, or there was an open-source recognizer library for this functionality:
I have a buddy who is blind. In the US, paper currency is all the same size and shape, so it's impossible to distinguish them by feel alone. He uses a system of folds to remember which bill is which, but if he drops one, or the cashier doesn't tell him what the denominations are, etc..., he ends up not know which bill is which. Occasionally that means he has to ask someone, despite having a 'routine' that is generally very effective.