The mobile device detects the position detection patterns in the picture frame captured by the mobile device camera. As shown in Figure 5, the mobile device overlays the fraction part of the mobile time as a complementary time marker in a time marker located at the relative position of the patterns. If the white part of the time marker is fully covered with a complementary time marker, the synchronization process is finished. If it is not fully covered and a white space remains, mobile time is corrected in accordance with the width of the white space. As shown in Figure 6, the relation between width n (px) and the synchronous error time t (sec.) is given by the following equation: