1. An image reading apparatus comprising: a reading unit configured to read an image of a document to generate image data; a storing unit configured to store the image data generated by the reading unit; a receiving unit configured to receive from a user, after the image data is stored by the storing unit, an instruction for executing character recognition processing on the image data stored by the storing unit; a character recognition unit configured to execute character recognition processing on the image data stored by the storing unit according to a reception of the instruction by the receiving unit; and a control unit configured to perform control, in a case where the image data generated by the reading unit is to be stored by the storing unit, to read an image of a document by the reading unit with a resolution that enables character recognition by the character recognition unit.