Program for correcting image distortion, apparatus for correcting image distortion, method for correcting image distortion, and recording medium storing program for correcting image distortion

An apparatus for correcting image distortion comprising:

• an image input means for inputting a picked-up image in which a paper face has been imaged;
• a geodesic line projection extraction means for extracting from the image that has been input by said image input means, a projection set of geodesic lines which are parallel with each other on a curved surface of the paper face, using the contents of said paper face as a clue;
• a ruling line projection extraction means for extracting from the projection set of geodesic lines that has been extracted by said geodesic line projection extraction means, a projection set of ruling lines which form a ruled surface corresponding to said curved surface of the paper face;
• a paper face curved surface estimating means for estimating said curved surface of the paper face from the projection set of the geodesic lines and ruling lines individually extracted by said geodesic line projection extraction means and said ruling line projection extraction means;
• and
• a distortion correction means for correcting distortion of the image input by said image input means, based on the curved surface of the paper face estimated by said paper face curved surface estimating means.

A method for correcting image distortion comprising executing on a computer:

• a geodesic line projection extraction step for extracting from an image in which a paper face has been imaged by an image-pickup device, a projection set of geodesic lines which are parallel with each other on a curved surface of the paper face, using the contents of said paper face as a clue;
• a ruling line projection extraction step for extracting from the projection set of geodesic lines that has been extracted by said geodesic line projection extraction step, a projection set of ruling lines which form a ruled surface corresponding to said curved surface of the paper face;
• a paper face curved surface estimating step for estimating said curved surface of the paper face from the projection set of the geodesic lines and ruling lines individually extracted by said geodesic line projection extraction step and said ruling line projection extraction step;
• and
• a distortion correction step for correcting distortion of the image input by said image-pickup device, based on the curved surface of the paper face estimated by said paper face curved surface estimating step.

A recording medium storing a program for correcting image distortion for executing on a computer:

• an image input function for inputting a picked-up image in which a paper face has been imaged;
• a geodesic line projection extraction function for extracting from the image that has been input by said image input function, a projection set of geodesic lines which are parallel with each other on a curved surface of the paper face, using the contents of said paper face as a clue;
• a ruling line projection extraction function for extracting from the projection set of geodesic lines that has been extracted by said geodesic line projection extraction function, a projection set of ruling lines which form a ruled surface corresponding to said curved surface of the paper face;
• a paper face curved surface estimating function for estimating said curved surface of the paper face from the projection set of the geodesic lines and ruling lines individually extracted by said geodesic line projection extraction function and said ruling line projection extraction function;
• and
• a distortion correction function for correcting distortion of the image input by said image input function, based on the curved surface of the paper face estimated by said paper face curved surface estimating function.