An image forming apparatus of this invention, when an exposure unit performs exposure, applies, to image data quantized by a first number of bits, compensation data for compensating for unevenness of the exposure intensity occurring on a photosensitive member caused by a lens array used in the exposure unit. The browser module displays a Web view page in a browser window within the dialog box of the application program, enabling a user to perform browser functions and application program functions by selecting an element in the Web view page. The other side of the housing has an attached fixing unit. PSTN interfacing by a call processing platform may be provided as a VoIP connection to the PSTN andor as POTS trunking. The inner cylinder is provided with a holder through-hole and a pin guide hole.