Patent ID: 8259362

Claim:
An image forming system comprising: a processor; memory storing computer-readable instructions that, when executed by the processor, cause the image forming system to provide: a first data storage unit that stores, in a memory area, image data, obtained by reading an image of a document, of a top line and of at least one designated line other than the top line which is predesignated among a plurality of lines of the image, the top line being the first line to be formed on a recording medium where a length of the recording medium along a crosswise orientation of each of the lines is longer than a length of the document along a crosswise orientation of each of the lines; a second data storage unit that generates difference data which indicates a difference between image data of at least one non-designated line, which is a line different from the top line and the at least one designated line, and image data of a line adjacent to the at least one non-designated line, and stores the generated difference data in the memory area; a comparing device that compares a length of the recording medium along a crosswise orientation of each of the lines with a length of the document along a crosswise orientation of each of the lines; a data discarding device that discards image data and difference data of one or more lines from the top line to a line just before the designated line in an area which is longer than the length of the recording medium from the image data and the difference data stored in the memory area when the comparing device determines that the length of the recording medium is shorter than the length of the document; and a data decompressing device that sequentially decompresses the image data and the difference data stored in the memory area to obtain non-compressed image data for each line among a plurality of lines of a copy of the image; and an image forming device configured to form the copy of the image on the recording medium, based on the non-compressed image data, the copy including the top line when a length of the recording medium along a crosswise orientation of each of the lines is longer than a length of the document along a crosswise orientation of each of the lines, but not including the one or more lines from the top line to the line just before the designated line when a length of the recording medium along a crosswise orientation of each of the lines is shorter than a length of the document along a crosswise orientation of each of the lines, wherein the plurality of lines of the image is read in a predesignated order, and lines of the copy are formed on the recording medium in an inverse order from the read order.