1. A non-transitory computer-readable medium storing a program causing a computer to execute an image processing method applied to an image sensing device, the image processing method comprising: (a) comparing a frame delta between a reference frame and a first frame with a predetermined threshold value to generate a first comparing result; (b) comparing a frame rate of the image sensing device with a minimum frame rate to generate a first difference and comparing the frame rate with a maximum frame rate to generate a second difference; and (c) adjusting a frame rate of the image sensing device according to the first comparing result but not adjusting an offset for a correlation window of the image sensing device, if the first difference and the second difference are larger than a predetermined difference; and (d) adjusting the offset according to the first comparing result but not adjusting the frame rate, if the first difference and the second difference are smaller than or equal to the predetermined difference.