Modern technology has enabled monitoring of large populations of live cells over extended time periods in experimental settings. Live imaging of cell populations growing in a culture vessel has been widely adopted in biomedical experiments. Such experiments create large numbers of time-lapse images, and the information embedded in these images holds tremendous promise for scientific discovery. The growing amount of such data calls for automated or semi-automated computer vision tools to detect and analyze the dynamic cellular processes, and to extract the information necessary for biomedical study.
Live cells are often of low contrast with little natural pigmentation; therefore, they usually need to be stained or fixed in order to be visible under bright field microscopy or fluorescence microscopy. However, fixing or staining may destroy the cells or introduce artifacts. Label-free imaging, in particular phase contrast microscopy, is highly desirable for live cell imaging because it allows cells to be examined in their natural state, and therefore enables live cell imaging over extended time periods. We focus in this chapter on analyzing time-lapse images from phase contrast microscopy.
