The accuracy of reading a barcode embedded in a printed document is maintained, and at the same time, the amount of toner and the like consumed is reduced. When document information read by scanning is analyzed and the density of the document information is higher than a predetermined threshold vale, that is, when the printed document has a space enough to contain the barcode, the density of the barcode is set such that the density of the barcode is decreased as compared with a case where the density of the document information is lower than the predetermined threshold value. By changing the size of dots and the distance between the dots and thus decreasing the density of the barcode, it is possible to reduce the amount of toner and the like consumed. Then, the set barcode is synthesized with the document information, and the synthesized image is output.