Keld Helmer-Petersen stayed at the art school, institute of Design, in Chicago. He was both a student and a guest teacher and his future work was influenced immensely by what he learned at school. He developed a graphic black and white aesthetic.

He grew increasingly experimental, engaging in abstract studies of light in urban spaces as well as in the darkroom. He turned silhouettes and fragments of wires and steel constructions into rhythmic, dynamic patterns. Upon his return to Copenhagen, he continued in his graphic style, finding the steel world of Chicago reflected in harbour areas and railways.