1. An image processing apparatus comprising: a scanner that inputs document image data obtained by scanning a document; and a processing unit comprising: a region segmentation unit that extracts a plurality of recognition target regions from the document image data input by the scanner; a first selecting unit that allows an operator to select, from the plurality of recognition target regions extracted by the region segmentation unit, recognition target regions to be recognized; a second selecting unit that allows an operator to select a recognition process to be executed for individual recognition target regions selected by the first selecting unit; and a determining unit that, based on each recognition process selected in the second selecting unit, determines, for each of the selected recognition target regions, whether each of the selected recognition target regions is to be transmitted to an external recognizing device and to be subjected to recognition processing in the external recognizing device, wherein the second selecting unit provides the operator with, as choices for the recognition process, a first choice of transmitting a recognition target region to an external recognizing device for subjecting the transmitted recognition target region to the recognition processing in the external recognizing device, a second choice of downloading a program from an external device and performing the recognition processing of a recognition target region by using the downloaded program, and a third choice of performing the recognition processing by using a recognition program stored in the image processing apparatus.