Yongyi Yang has research interests in the fields of image processing, medical imaging, machine learning, color vision, and optical information processing. He has authored or co-authored over 300 publications in these areas. His current research topics include: 1) tomographic image reconstruction methods for cardiac and pediatric kidney imaging, 2) Computer-aided diagnosis techniques for breast cancer detection in mammography, 3) Modeling of image similarity from human observers for content-based image retrieval, 4) Construction of brain atlas of adults without dementia for neuroimaging studies of age-related neurological diseases, 5) Multispectral infrared imaging of the iris for diagnostic ophthalmology, and 6) Optimization of the use of video technologies in policing.