A measurement apparatus, which measures the relative position and orientation of an image-capturing apparatus capturing images of one or more measurement objects with respect to the measurement object, acquires a captured image using the image-capturing apparatus. An optical card containing an imaging lens is slidably received in a rear guideway situated between the arms. The shielding means being flush with or almost flush with the outside face of the pad and extending along the length of the outside face of the pad so that the electric field generated by the current and return electrodes is substantially eliminated in the pad and in the vicinity of the measurement electrodes. A magnitude of a discontinuous component in a frequency domain belonging to the block boundary is adjusted based on a magnitude of a corresponding discontinuous component selected from a pixel contained entirely within a block adjacent the block boundary.