An image data acquisition unit (101) that obtains image data comprising a plurality of pixels and including an optical recognition code. A mixed color determination unit (102) changes the color of a first pixel from a third color to either a first or second color, if a determination is made that all colors in at least one second pixel are different from the third color, said second pixel being positioned at a predetermined distance from a first pixel having the third color, said first pixel being among a plurality of pixels constituting the optical recognition code included in the obtained image data. A read processing unit (105) reads the optical recognition code included in the image data after the color has been changed.
展开▼
