Patent ID: 7079265

Claim:
A method of correcting an image produced by imaging a surface of an opened book facing upward from above of the surface of said book by a camera having a non-fixed positional relation with said book, comprising the steps of: imaging the surface of said opened book to generate an electric signal representing the image of the surface of said book; measuring a distance between said camera and the surface of said book; extracting, according to said electric signal, an edge image corresponding to an upper or lower end of said book in the image represented by said electric signal; determining a position of said camera relative to the surface of said book according to said extracted edge image; determining a height distribution of said upper or lower end of the surface of said book according to said measured distance, said extracted edge image of the upper or lower end of said book, and said position of said camera relative to the surface of said book; determining a height distribution of an entire image of the surface of said book on the supposition that said book is at the same height in the direction in which said book is opened; and converting, according to said determined height distributions, said image signal into a signal representing an image of the surface of said book as a plane surface.