A method for mounting one or more printing plate segments on a carrier sheet. The method comprises importing a file into a computer associated with a mounting unit. For each printing plate segment, the file includes a printing plate segment identifier, information regarding alignment of registration marks relative to the carrier sheet; and image data corresponding to a characteristic pattern associated with each printing plate segment. A composite image depicting the image data corresponding to the characteristic patterns is then displayed on a display in the predetermined arrangement of one or more printing plate segment locations and orientations. A mounting unit and a printing system and computer readable media programmed with instructions for performing the method are also described.