an operation panel that enables a user to carry out an input operation, and that carries out a screen display;

an expansion board recognizing unit that determines whether a detachable expansion board that realizes a watermarking function is mounted on the image forming apparatus;

an operation panel controller that outputs a display concerning the watermarking function on the operation panel when the expansion board recognizing unit determines that the expansion board is mounted;

an extended function processor that sets extended function permission information indicating acceptance or non-acceptance of the use of the watermarking function to the user in advance;

a distribution destination storage unit that stores distribution destination information to which a distribution destination of distributing an input image via a network and the extended function permission information are related, wherein

the operation panel controller displays a distribution setting screen for enabling the user to assign the distribution destination on the operation panel and outputs the display concerning the setting of the watermarking function to the operation panel when the use of the watermarking function is set to the extended function permission information of the distribution destination information corresponding to the distribution destination assigned from the distribution setting screen, and

the operation panel controller is configured to display a first watermark setting screen including both a scanner ID field and an optional character string field based on a retrieved first security level corresponding to a user name input to the operation panel, and display a second watermark setting screen including only the optional character string field based on a retrieved second security level corresponding to a user name input to the operation panel.