1. A method for illumination-independent change detection between a pair of registered images, comprising: a. providing a first original gray-level image, a second original gray-level images, a first negative image related to said first original image and a second negative image related to said second original image, b. extracting respective pluralities of blobs from each of said first and second original images and each of said first and second negative images, c. matching each extracted blob in said first original and negative images with each extracted blob in said second original and negative images to obtain matched and unmatched blobs, and d. testing all said unmatched blobs to identify blobs of change, whereby said blobs of change indicate a change detected by a method that is exact, fast, robust, illumination-insensitive and has low time-complexity.