When computation of a three-dimensional measurement processing parameter is completed, accuracy of a computed parameter can easily be confirmed. After a parameter for three-dimensional measurement is computed through calibration processing using a calibration workpiece in which plural feature points whose positional relationship is well known can be extracted from an image produced by imaging, three-dimensional coordinate computing processing is performed using the computed parameter for the plural feature points included in the stereo image used to compute the parameter. Perspective transformation of each computed three-dimensional coordinate is performed to produce a projection image in which each post-perspective-transformation three-dimensional coordinate is expressed by a predetermined pattern, and the projection image is displayed on a monitor device.