A method of manufacturing a semiconductor device that includes providing a substrate having a pattern formed thereon. A scanning electron microscope (SEM) image is generated that includes a boundary image showing an edge of the pattern. A blended image is generated by performing at least one blending operation on the SEM image and a background image aligned with the boundary image. Contour data is generated by binarizing the blended image on a basis of a threshold value. The threshold value is determined by a critical dimension of the pattern.