An image processing apparatus includes a scanning mechanism, first and second
memories, an image accumulating mechanism, a detecting mechanism, a determining
mechanism, and a code assigning mechanism. The first memory stores a reference
dot pattern indicating an anti-copy background dot pattern. The second memory stores
image data. The image accumulating mechanism accumulates image data of an original
image into the second memory. The detecting mechanism detects a background dot
pattern embedded in a background image included in the image data of the accumulated
original image. The determining mechanism compares the detected background dot
pattern with the reference dot pattern and determines whether the detected background
dot pattern is substantially identical to the reference dot pattern. The code assigning
mechanism assigns an identification code to the image data having the detected
background dot pattern when the detected background dot pattern is determined as
substantially identical to the reference dot pattern.
