1. Computer Vision for Human–Computer Interaction Laboratory, Karlsruhe Institute of Technology, Karlsruhe, Germany
2. Center for Digital Accessibility and Assistive Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany
3. Computer Vision for Human–Computer Interaction Laboratory and the Center for Digital Accessibility and Assistive Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany