In the following year, Han joined O.K. Harris Gallery, owned by Ivan Karp where he regularly exhibited until 1984. Throughout the early 1970s, Han honed his spray painting techniques by modeling Seurat’s Post-Impressionist form to create a color separation method, which eventually became his signature “dot” style. In employing his original technique, he completed several photo-realist works with New York City scenes as his main subject, including “Subtle New York Cityscapes” ( 1971 ) and “Soho District” ( 1974 ), all of which his own photography and documentation served as main composition sources for larger paint renderings.