RESULTS AND DISCUSSION
As seen in Figure 3, it is obvious that the proposed routines are correctly capable of finding the LED centers with some observable failures. During the course of our experiments, we tested the correctness of the routines with respect to different input images captured from several LED arrays. Due to the fact that some intermediate images were manually adjusted during processing in order to remove the defects and improve their quality before locating LED centers, it was then difficult to measure exactly the percent correctness. To reflect the operational correctness, the results presented here were produced without any manual adjustment to the processes on the right side of Figure 2. The allowable adjustment to the processes on the left side was only to remove all background caused by a non-uniform illumination. Some results are illustrated in Figure 4.