A method for converting an electronic document (ED) having a first format includes comparing an original width of the ED with a predetermined width and an original length of the ED with a predetermined length; splitting the ED into pieces in a width direction when the original width is greater than the predetermined width, and splitting the ED into pieces in a length direction when the original length is greater than the predetermined length, wherein each piece has a width and length less than or equal to the predetermined width and length; storing information representing geometric relationships of the pieces; converting the pieces from the first format into a second format; outputting the converted pieces as first output EDs; and outputting a second output ED having the second format, wherein the second output ED incorporates the first output EDs according to the information when displayed by a viewer application.