A method of computational lithography includes collecting a critical dimension (CD) data set including CD data from printing a test structure including a set of gratings which provide a plurality of feature types including different ratios of line width to space width, where the printing includes a range of different focus values. The CD data is weighted to form a weighted CD data set using a weighting algorithm (WA) that assigns cost weights to the CD data based its feature type and its magnitude of CD variation with respect to a CD value for its feature type at a nominal focus (nominal CD). The WA algorithm reduces a value of the cost weight as the magnitude of variation increases. At least one imaging parameter is extracted from the weighted CD data set. A computational lithography model is automatically calibrated using the imaging parameter(s).