Isidore Baron Opsomer was a Belgian painter, draughtsman and engraver. He studied at the art academies in Lier and Antwerp. A scholarship enabled him to stay in Rome for ten months in 1904 and afterwards, to travel through France, Germany and Austria. On his return to Belgium, he became a teacher at the Royal Academy of Fine Arts in Antwerp. At the outbreak of World War I, Opsomer fled with his family to London, but returned in 1915 to organise exhibitions in the Netherlands on behalf of the Belgian government. His early work consists mainly of landscapes and still lifes. From the mid-1920s, he worked mainly as a portraitist, painting numerous official portraits of politicians and members of the Belgian royal family. From 1926 to 1949, Opsomer was director of the Nationaal Hoger Instituut voor Schone Kunsten in Antwerp. In 1940, he was ennobled as Baron.