Born in Zurich, Switzerland, although she was registered in Frankfurt, Germany, in 1913. Studied photography with German photographer Paul Wolff, a Leica specialist. In 1937 Hildegard came to Brazil to meet her future husband Walther Rosenthal. The next year she started working as photographer and director in the Press Information agency, which sent articles about Brazil abroad. In addition to the reports she made to the agency, Hildegard published photos in various magazines and newspapers such as O Estado de S. Paulo, Folha da Manha, Geography Magazin (London) and A Cigarra, among others. Her work stands out for urban views of the city of São Paulo and the emphasis given to the human element in her images. She photographed from a photojournalistic perspective. In 1977 she won the award for Best Photographer in the XIV International Biennial of São Paulo. She died in 1990 in São Paulo.