1. A method of difference sensing, the method comprising the steps of: producing a reference image using temporal averaging and spatial averaging, the temporal averaging and spatial averaging comprising taking a series of images of the same scene, spatially aligning the series of images, and then summing corresponding pixel values of the series of images to create a temporal average of pixel intensity; producing a test image; computationally comparing the reference image with the test image to arrive at a resulting difference image, such that the temporal averaging and spatial averaging effectively isolates in the difference image coherent changes imbedded in a complex and rapidly changing environment from transient changes inherent to the complex and rapidly changing environment.