1. A method for evaluating an output pattern printed on a medium, the evaluating method comprising the steps of: storing a reference pattern, wherein the output pattern is printed on the medium based correspondingly on the stored reference pattern; rendering a scan based instance of the output pattern, wherein the rendered scan based instance comprises: a set of features at least corresponding to the printed output pattern; and zero or more defect features in addition to the set of features at least corresponding to the printed output pattern, the zero or more defect features comprising zero or more printed defect features; computing a difference image based on a comparison of the rendered scan based instance to the stored reference pattern, the computed difference image comprising the zero or more defect features of the rendered scan based instance; and evaluating the computed difference image upon the zero or more defect features comprising at least one defect feature in relation to a proximity of at least one feature to a location of one or more picture elements (pixels) of the stored reference pattern.