1. An image processing system comprising: a display apparatus; an image capturing apparatus; and an image processing apparatus, the display apparatus comprising a display unit to display an image on a display medium, the display medium including a first display medium and a second display medium, the image capturing apparatus comprising an image capturing unit to output a captured image obtained by imaging a subject, and the image processing apparatus comprising: a first acquiring unit to acquire a first pattern image including a pattern for being displayed on the display medium by the display unit; a second acquiring unit to acquire, as a second pattern image, a captured image obtained by capturing an image obtained by displaying the first pattern image on the display medium with the display unit, the capturing being performed by the image capturing apparatus from a position of the display medium; and an image processing unit to compare the first pattern image with the second pattern image, and to apply a process of deforming a shape based on the second pattern image into a shape of the first pattern image to a rectangular target image according to a result of the comparison, wherein the display unit is configured to display the target image deformed by the image processing unit on the display medium, wherein the first and the second display media are placed such that respective display surfaces of the first and the second display media appear to continue to each other when viewed by a person in at least one position, and wherein the display apparatus is configured to respectively display images obtained by dividing one image on the first and the second display media.