An instruction of image processing for an image and an object included in the image is received from a client. The operation environment of the client is stored as the metadata of the object included in the image. When an instruction is input to re-evaluate the attribute of the object included in the image, a record is made as metadata indicating that the attribute has been re-evaluated. Upon receiving another image different from the image, when the operation environment of a client which has given an instruction to perform image processing of the other image is identical to the operation environment of the client which is stored by the storage unit, and the record is in the recording unit indicating that the attribute has been re-evaluated, the attribute of the received other image is re-evaluated.