The publisher of the postcard or a series of cards is the one who takes the financial risk of the edition. It is generally the one who orders printing from the card printer. The photograph is provided by the photographer or is drawn by the illustrator.

Some printers are themselves publishers of their cards
Some photographers and illustrators are also publishers of their maps
It is therefore still not easy to distinguish the publisher from the printer, the photographer, the artist.

In case of doubt, you must indicate in the editor's file that he is also a printer and indicate in the map the identical publisher and printer as long as the distinction is not made