Abstract: At least one image of the environment is taken using either an image capturing device of the monitoring system. Based on the image of the environment, at least one background image is generated. The background image, which comprises a plurality of pixels, is divided into pixel blocks. In each pixel block, at least one data cluster is formed using at least one feature of the pixels in the pixel block. The data cluster formed in each pixel block is described as a data distribution having a mean value and a standard deviation from the mean value. After generating the background image, a subsequent image is taken by the monitoring system. Each pixel of the subsequent image is compared with the data cluster of the block of the background image correspond to the pixel, and a first discrepancy value is generated accordingly.