A reference image is generated based on an illumination condition and element information of a specimen. The reference image includes a figure indicating a characteristic X-ray generation range, a numerical value indicating a characteristic X-ray generation depth, or the like. The reference image changes with a change of an accelerating voltage, a tilt angle, or an element forming the specimen. The reference image may include a figure indicating a landing electron scattering range, a figure indicating a back-scattered electron generation range, or the like.