What is the origin of the idiom "get the picture" and when to use it?

The origin of the idiom "get the picture" is not tied to a specific historical reference, but it draws upon visual imagery as a metaphor for understanding. It is commonly used in conversations, discussions, or explanations where there is a need to confirm comprehension. It can also be used in situations where there is a need to emphasize or clarify a point and to prompt the listener to fully understand the intended meaning.