Patent ID: 8059296

Claim:
An image forming apparatus comprising: an extracting unit that extracts fiber information from paper media; a first storage unit that synthesizes and stores, as first fiber information, fiber information extracted from pages of a first paper medium consisting of a plurality of pages using the extracting unit; a second storage unit that synthesizes and stores, as second fiber information, fiber information extracted from pages of a second paper medium consisting of a plurality of pages using the extracting unit; and a comparing unit that compares the first fiber information and the second fiber information and determines whether they match each other, wherein if f 1 (x,y) represents grayscale image data in the first fiber information and Î± 1 (x,y) represents mask data in the first fiber information, and f 2 (x,y) represents grayscale image data in the second fiber information and Î± 2 (x,y) represents mask data in the second fiber information, then, the match determined using a collation error E(i,j) is indicated as E â¡ ( i , j ) = âˆ‘ x , y â¢ â¢ Î± 1 â¡ ( x , y ) â¢ Î± 2 â¡ ( x - i , y - j ) â¢ { f 1 â¡ ( x , y ) - f 2 â¡ ( x , y ) } 2 âˆ‘ x , y â¢ â¢ Î± 1 â¡ ( x , y ) â¢ Î± 2 â¡ ( x - i , y - j ) . ( 1 )