Disclosed is an image processing apparatus, comprising a shading-information acquisition device 1 for picking up an image of an actual sample, a shading-information calculation section 201 for calculating shading information using the image acquired by the shading-information acquisition device 1, and storing the calculated shading information in a shading-information storage section 101, in association with the value of a parameter including an image pickup condition during the pickup of the image, a parameter calculation section 203 for calculating a specific value of the parameter at given position of a virtual 3-dimensional model, a shading-information read section 204 for allowing the shading-information storage section 101 to read the shading information corresponding to the calculated parameter value therethrough, and a shading processing section 206 for calculating a brightness value at a target position HP of the virtual 3-dimensional model, using the read shading information and a texture stored in a texture storage section 103.