A barcode-embedding area is obtained in a color image based on expression possibility by the juxtaposed additive color mixture and possibility of reading of pixels separately by a barcode reader (S11), a color image in the barcode-embedding area is expressed by the juxtaposed additive color mixture, and color images for the code area and the background area, which are readable by the barcode reader, are created (S12, S13), a color-image-superimposed barcode image is created by using the color images for the code area and the background area, and the same color-image-superimposed barcode image is embedded in the barcode-embedding area (S14), and the color-image-superimposed barcode image and the original color image are corrected if necessary (S15, S16).