1. An image reading apparatus comprising: a reading unit configured to read an image of a document to generate image data; a character recognition unit configured to execute character recognition processing; a first receiving unit configured to receive a storage instruction for storing the image data in a storage unit; a second receiving unit configured to receive a character recognition instruction for causing the character recognition unit to execute the character recognition processing on the image data which has been stored in the storage unit in accordance with the storage instruction; and a determining unit configured to determine, in accordance with the storage instruction, a predetermined resolution as a reading resolution by the reading unit, wherein at least one of the character recognition unit and the determining unit is implemented by a processor and a memory.