1. An image reading apparatus comprising: an image data acquiring unit configured to acquire document image data including more than one set of page image data; an image reading unit configured to read an image located at a predetermined page position from the acquired set of page image data; a conversion unit configured to recognize the read image of the predetermined page position and convert the recognized image into text data; and an order assigning unit configured to assign page number order to the set of page image data according to value information represented by the converted text data, wherein the image reading unit is configured to read more than one images located at more than one predetermined page positions from the set of page image data, reverse an orientation of the set of page image data when the images of the predetermined page positions are not recognized, and read more than one reversed images located at the more than one predetermined page positions from the reversed set of image data, and the conversion unit is configured to recognize at least one reversed image of the reversed images of the page positions and convert the recognized reversed image into text data.