Figure 4Master program.The master program exhibits variations in the wave forms of the target images of each subsystem defined in the slave program. Figure 4 exhibits www.selleckchem.com/products/Tipifarnib(R115777).html the full-scale images (640 �� 480) of two camcorders and the wave forms of horizontal (X) and vertical (Y) displacements in red and blue lines, respectively. 2.2.1. Conversion of Images into Binary Images To convert grayscale images into binary images, we should begin by determining a suitable threshold value that concisely recognizes the position of target points. Therefore, an adaptive threshold technique using Otsu’s method [11] is implemented in this system. The process of binary image conversion using the adaptive threshold value is summarized in Figure 5. Figure 6 illustrates the significant difference between applying the adaptive threshold algorithm and not applying it.
As shown in Figure 6(a), some target points (white spots) can be missed when using an unreasonable threshold value, whereas there is little chance of missing targets when deploying the adaptive threshold algorithm, shown in Figure 6(b). Figure 7 shows some typical target panel recognitions in different situations using adaptive threshold technique.Figure 5Flowchart of binary image conversion.Figure 6Target recognition. (a) The same threshold value for four spots without adaptive threshold technique and (b) each threshold value for each spot using adaptive threshold technique.Figure 7Target recognition in various situations with adaptive threshold technique: (a) dark condition, (b) bright light, (c) bright light in the upper right corner, and (d) bright light in the upper left corner.
2.2.2. System Calibration for Time Synchronization Time calibration process needs to be carried out to maintain time synchronization between the master PC and the two slave PCs, and this important process is clearly shown in Figure 8. The master PC measures the time lag due to the wireless communication and differences in internal time clocks between the master and slave PCs. The master PC first sends the same size of dummy time data to all the slave PCs. When the data reach the slave PCs, they immediately return the received dummy data to the master PC. Then the master PC measures the time gap between the sending and receiving time to calculate the time delay between all the subsystems.
Subsequently, the master PC sends the internal clock time and the time delay of the slave PCs to each subsystem. Finally, the slave PCs adjust the internal Entinostat clock according to the time data received from the master PC. Time is calibrated every 60s, so the synchronization of time between the master PC and slave PCs remains consistent.Figure 8Time synchronization process: (a) time synchronization algorithm and (b) diagram of time synchronization process.