1. An image processing method executed by an image processing apparatus, the method comprising: a dividing step of dividing a registered document image into a plurality of regions based on image attributes; a transforming step of transforming an image of each region divided in the dividing step into plural types of output information, wherein a data format of each type of the output information is expected to be used frequently; a generating step of generating structured document information which indicates a structure of the registered document image by associating the output information with respective regions; a storing step of storing the structured document information and the plural types of output information for each region in a memory as a registered document; a first obtaining step of obtaining information of an output destination of the registered document stored in the memory; a determining step of determining types of the output information to be output for respective regions in the registered document, based on both the information of the output destination and the image attributes of the respective regions; a second obtaining step of obtaining a plurality of the output information corresponding to the determined types for the respective regions; a combining step of combining the plurality of the output information obtained for the respective regions into combined document data; and an outputting step of outputting the combined document data to the output destination, wherein in the second obtaining step, if the output information corresponding to a type determined for a region is stored in the memory, the output information corresponding to the determined type is obtained for the region from the memory, wherein in the second obtaining step, if the output information corresponding to a type determined for a region is not stored in the memory, the output information corresponding to another type is obtained from the memory, and the obtained output information is transformed into the output information corresponding to the determined type for the region.