1. An image forming apparatus comprising: a storage portion storing image data that is an output target; a preview image generating circuit that generates a plurality of preview images from the image data based on a plurality of output settings; an output image generating circuit that generates a plurality of output images from the image data based on the plurality of output settings; a data information obtaining circuit that obtains a plurality of pieces of data information from a plurality of pieces of output image data of the plurality of output images, and discards the plurality of pieces of output image data from which the plurality of pieces of data information were obtained, the plurality of pieces of data information being different from each other in correspondence with the plurality of output settings; and a display circuit that displays the plurality of preview images in alignment, and the plurality of pieces of data information respectively in connection with the plurality of preview images that correspond thereto via the plurality of output settings.