Abstract: For the fast connectedcomponent labeling problem of the optical imaging sensor for the last adjacent RVD, the twoscanning algorithm is improved via combining the procedures of labeling merge and second scanning. The fusion of target prerecognition and the labeling algorithm is presented when considering the mutual constraint conditions and some prior knowledge. The simulation results shows that both of them can improve the efficiency of valid connectedcomponent labeling (CCL). The improved CCL costs less than 98ms in average when repetitively dealing with an image with the size of 1 024×1 024, and has the ability of realtime implementation.