A method, system and a computer program product for evaluating a object; the method includes: (i) obtaining an image of an area of the object; wherein the area comprises multiple arrays of repetitive structural elements that are at least partially surrounded by at least one group of non-repetitive regions; wherein non-repetitive regions that belong to a single group of non-repetitive regions are ideally identical to each other; wherein the non-repetitive regions are arranged in a repetitive manner; and(ii) providing an evaluation result in response to a comparison between image information of a first sub-area to image information of a second sub-area that is proximate to the first sub-area; wherein the first sub-area comprises a first array of repetitive structural elements and a first non-repetitive region; wherein the second subarea comprises a second array of repetitive structural elements and a second non-repetitive region.