Please refer to FIG. 4. FIG. 4 is a flow chart of a method of acquiring detection zone in image according to another embodiment of the present disclosure. Steps S01 to S05 and steps S01′ to S05′ disclosed in FIG. 4 are the same as steps S01 to S05 disclosed in FIG. 2, which will not be further described herein. However, the method of acquiring detection zone in image disclosed in FIG. 4, the images acquired in step S01 are different from the images acquired in step S01′; the moving traces obtained in step S03 are different from the moving traces obtained in step S03′. Therefore, a first detection zone obtained by performing the clustering procedure (step S05) on the moving traces obtained in step S03 is different from a second detection zone obtained by performing the clustering procedure (step S05′) on the moving traces obtained in step S03′. In addition, in the present embodiment, steps S01 to S05 preferably are performed prior to steps S01′ to S05′.

In detail, after obtaining the first detection zone in step S05 and displaying a first image having the first detection zone in step S07, the computing device then performs steps S01′ to S05′ to obtain the second detection zone, wherein the number of the first detection zone and the second detection zone can be one or more, the present disclosure is not limited thereto. In other words, the first image and the second image described in steps S01 and S01′ preferably are real-time images that are acquired at the same image acquiring scene but at different timing.