A method of identifying motion within a field of view includes capturing at least two sequential images within the field of view. Each of the images includes a respective array of pixel values. An array of difference values between corresponding ones of the pixel values in the sequential images is calculated. A sensitivity region map corresponding to the field of view is provided. The sensitivity region map includes a plurality of regions having different threshold values. A presence of motion is determined by comparing the difference values to corresponding ones of the threshold values.