Compensation of global movement for improved tracking of cells in time-lapse confocal microscopy image sequences

(published online Mar. 5, 2007) A bottleneck for high-throughput screening of live cells is the automated analysis of the generated image data. An important application in this context is the evaluation of the duration of cell cycle phases from confocal time-lapse microscopy image sequences, which typically involves a tracking step. The tracking step is an important part since it relates segmented cells from one time frame to the next. However, a main problem is that often the movement of single cells is superimposed with a global movement. The reason for the global movement lies in the high-throughput acquisition of the images and the repositioning of the microscope. If a tracking algorithm is applied to these images then only a superposition of the microscope movement and the cell movement is determined but not the real movement of the cells. In addition, since the displacements are generally larger, it is more difficult to determine the correspondences between cells. We have developed a phase-correlation based approach to compensate for the global movement of the microscope by registering each image of a sequence to a reference coordinate system. Our approach uses a windowing function in the spatial domain of the cross-power spectrum. This allows to determine the global movement by direct evaluation of the phase gradient, avoiding phase unwrapping. We present experimental results of applying our approach to synthetic and real image sequences. It turns out that the global movement can well be compensated and thus successfully decouples the global movement from the individual movement of the cells.