In the last thirty years Umberg’s monochrome painting has been investigating into the corporeity of colours considered as a radical perception and a totalizing experience. His works use various surfaces on which layers of painting are superimposed, thus investigating the material nature of paintings. In 1982 he meet painter Joseph Marioni in New York and together they formulated the principles of "Radical Painting". Through many personal and collective exhibitions he is present in museums and galleries throughout the world and is also one of the first curator artists on the contemporary scene, constantly in search of a formal language among the works exhibited. Among the museums that have hosted his works mention must be made of P.S.1 (New York), San Francisco Art Institute (San Francisco), Kasseler Kunstverein (Kassel), Staatliche Akademie der Bildenden Künste (Karlsruhe), Museum für Moderne Kunst (Frankfurt Am Main), Peggy Guggenheim Collection (Venice), Unlimited-Art Basel 2012. He lives and works in Cologne, Germany.