1. An image processing device, comprising: an image scanning part that scans an image on a document and generates image data based on the image; an input part that accepts an input designation of a division number into which the image data of the document generated by the image scanning part is divided, and an output resolution of output image data created based on the image data; a division processing part that creates divided image data by dividing the image data of the document by the division number accepted by the input part; a controller that calculates a scan resolution based on the division number and the output resolution of the output image data; and a data output part that outputs the divided image data as the output image data, wherein the controller controls the image scanning part to scan the image on the document at the calculated scan resolution.