An image forming system is provided. One or more embodiments sets forth an image forming method using printing data that includes a plurality of strip information including a plurality of images, respectively, segmented into a plurality of regions by rendering at least one page from a file, and that includes unique information having information on respective number indicators allocated to the plurality of strip information The method includes sequentially receiving the unique information and the plurality of strip information, detecting an intended number of the plurality of strip information configuring the page based on the received unique information, determining whether all of an intended plurality of strip information configuring the page are received by comparing the intended number of the plurality of detected strip information with a detected number of the received plurality of strip information, and performing printing using the plurality of received strip information based on the determining.