1. In a method for detecting defects in inspecting structured surfaces, in particular masks, LCD's, printed circuit boards and semiconductor wafers, using specific image point features of structures and defects of a recorded image of a surface in which zones of the image having similar image point features are compiled by image point classification and a behavior of image point features of an image point is analyzed with reference to its neighboring image points by structure classification, the improvement comprising the step of: generating a gray-value intermediate image containing edge structures and corner structures and serving for structure classification in an image point classification of the recorded image, the generating of the intermediate image including a step of describing distributions of image point features of selected random samples which correspond at least to a number of defect-free surface portions with distinct features in a feature space plotted by a number of image point features by means of probabilities which are transformed into grayscale values.