Image science has been extensively used for characterization and optimization of high-energy medical imaging modalities, such as CT, PET, etc., but its application to biomedical imaging modalities is still immature. In this talk, image science concepts, such as task-based assessment of image quality, system characterization and optimization, statistical decision theory, observer study, etc., are introduced focusing on the application to optical coherence tomography, frequency-domain diffusive imaging, and photoacoustic imaging.