Tuesday, March 3, 2009 531a correction for photobleach and photoconversion using nonlinear fitting, cell motion compensation based on hierarchical block matching, and spatiotemporal filtering. Two xy maps are generated to represent the maxima of fluorescent intensity change and the corresponding time, respectively. Flash events are identified via thresholding and segmentation based on these maps. Validation of the algorithm is performed on SNR-controlled synthetic data sets produced by embedding typical flash events in real images. With the aid of Flash Sniper, we examined~ 1600 flashes in cardiac myocytes and revealed distinct substructures in their rising kinetics. In sum, the analytical tool developed in this study will facilitate the studies of the mechanisms of superoxide flash and its application in health and diseases.