Understand, be informed about or be involved in a particular situation or activity. For example, The new ambassador wanted to be in the picture for every event, small or large. This term is also used in such locutions as
put someone in the picture, meaning “to inform or include someone,” as in Put me in the picture about the new staff, or
out of the picture, meaning “to be left ignorant of or excluded from some activity,” as in The local authorities were out of the picture when it came to drug dealers.
[ Early 1900s