1. A method of obtaining feedback information, which relates to fabrication of patterns on a wafer based upon fabrication data, the fabrication data derived from design data, comprising: capturing for at least one inspection region at least one image of patterns within the inspection region using an imaging device; automatically generating from data selected from the fabrication data and the design data, a reference pattern for the inspection regions, the reference pattern comprising a machine-readable representation of at least one of (a) one or more line segments and (b) one or more curves; detecting edges within each of the images; determining, from the detected edges, one or more measurements for each of the selected patterns; and processing the measurements to form statistical information and obtain the feedback information; wherein the measurements are grouped into a plurality of groups for statistical analysis by using at least one of (i) line widths of patterns in the data, (ii) orientations of patterns in the data, (iii) length of patterns in the data, (iv) space between patterns and adjacent patterns in the data; until each distribution of the grouped measurements becomes a normal distribution, and wherein the feedback information is feedback information for an Optical Proximity Correction (OPC) rule.