That "image table" you speak of is the tag you created at the controller scope.
When a produce/consume connection is initiated by a consumer, a deep conversation between it and the producer takes placed. This includes information about the constitution of the data exchanged (UDT name, size). If the parties are mutually agreeable in having a) a definition of said type at each endpoint and b) an instance of each at the endpoint, then an endless conversation containing precisely the bits defined in those types will ensue*.
Which is to say: This exchange takes place after *both* controllers have the same shared data type, data type name, and data type size.
* until a cable is unplugged, a cable is broken, network switch(es) linking the nodes fails, a PLC fails, both PLC fails, or the alleged heat death of the universe occurs**
** whichever comes first