1. A method for assessing the presence or absence of lesion(s) in an image, comprising a) estimating, using at least one computer, at least one subset of the image, whereby each subset is a candidate lesion area having a visibility, and estimating the background variation of the image in an area surrounding the candidate lesion area, wherein the background variation is estimated by a1) estimating the mean and standard derivation of the gradient magnitude pixels of an area defined surrounding the candidate lesion area, determining a lower threshold or above an upper threshold for the gradient magnitude pixel, a2) iteratively removing an out-lying gradient magnitude pixel below a lower threshold or above an upper threshold, and re-estimating the mean and standard deviation of the remaining gradient magnitude pixels, determining a second lower and a second upper threshold for the gradient magnitude pixels, until no out-lying gradient magnitude pixels are found, and a3) estimating the background variation from the mean and standard deviation estimated in a2), b) correcting the visibility of the candidate lesion area with the background variation, comparing the corrected visibility with a predetermined visibility threshold for lesions in that area, or correcting a predetermined visibility threshold with the background variation, comparing the visibility of the candidate lesion area with the corrected predetermined visibility threshold, c) classifying the candidate lesion area detected in a) with respect to the threshold obtained in step b) and as a lesion or not, d) optionally repeating steps a) to c) until all candidate lesion areas have been classified.