1. A method of measuring a 3 dimensional (3D) image, the method comprising: measuring a brightness of a first illumination source by controlling, by a central control unit, a module control unit and an image acquisition unit; measuring a phase-to-height conversion factor by controlling, by the central control unit, the module control unit and the image acquisition unit when the brightness of the first illumination source is measured; determining by the central control unit whether the measurement is performed in a normal inspection mode when the brightness of the first illumination source and the phase-to-height conversion factor are measured; measuring a 3D shape of target objects on a board according to the normal inspection mode by controlling, by the central control unit, the module control unit and the image acquisition unit when it is the normal inspection mode as a result of the determination; searching a database and determining, by the central control unit, whether bare board information about the board is included in the database when it is not the normal inspection mode but teaching-based inspection mode as a result of the determination; performing bare board teaching by controlling, by the central control unit, the module control unit and the image acquisition unit when the bare board information is excluded in the database; measuring the 3D shape of target objects on the board according to a teaching-based inspection mode by controlling, by the central control unit, the module control unit and the image acquisition unit when the bare board information is included in the database or when bare board teaching information is generated in the performing of the bare board teaching; and analyzing by the central control unit whether the board is normal or abnormal by using information about the measured 3D shape of target objects on the board when the 3D shape of target objects is measured according to the normal inspection mode and the teaching-based inspection mode.