Gunnar S. Gundersen (1921-1983) was one of Norway's foremost post-war modernists and leading in Scandinavia within the concrete art, a non-figurative art style mainly based on shapes and colours. He was influential in the development of non-figurative painting in Norway, alongside artists like Jakob Weideman, Gudrun Kongelf, Odd Tandberg, Lars Tiller and Anna-Eva Bergman. These artists were influenced by an international concrete painting that had appeared in the early 1930s. Gunnar S., as he was called, soon developed an original painting, combining "soft edge" with "hard edge". The painting is characterized by a sense of space and perspective, even with the emphasis on the surface. Behind the experimentation was a strong theoretical interest in perception psychology, among other subjects.

Gunnar S. taught for several years at the Norwegian Technical College in Trondheim, where theory and experimentation was an important part of the curriculum. He made a series of room decorations, both private and public. Together with Gundrun Kongelf and Ludvig Eikaas, he decorated the facade of the Artists Association in Oslo, a mural in Den Kemiske Fabrik Norden in Oslo (both 1950), a mural in Arne Korsmo's villa in Oslo (1954-55) and decorations of Rikstrygdeverket (1960). He also decorated building for Bytårnet School in Moss (1961), Brittania Hotell in Trondheim (1963), the Brage-Fram building in Oslo (1968), Jotun Factories in Sandefjord (1970), Høyenhall School in Oslo (1972) and the laboratory building and Ullvål hospital in Oslo (1979).