1. A method for the extraction of shadows in noisy images, comprising the following steps: capturing an image; subdividing the image into a plurality of pixels; defining a square odd matrix for every pixel having said pixel in the center; applying an algorithm using a device to the matrices; displaying an error map of said image; wherein the algorithm is a contour algorithm, comprising the follow steps: computing averages for each corner of the matrix; computing averages for the top, bottom, left and right sides; computing the maximum variance between these eight averages; and comparing the maximum variance with a present value.