1. An apparatus for processing an image of a sample having a pattern that is obtained by scanning electron microscope, said apparatus comprising: a memory for storing a backscattered electron image obtained by the scanning electron microscope; a processor for extracting contour data of the pattern from the backscattered electron image; wherein said memory stores a secondary electron image of the sample in addition to the backscattered electron image; and said processor executes processing for combining the backscattered electron image and the secondary electron image, and extracts the contour data based on the combined image.