Automatic information retrieval from data embedded printing images using correction of rotational angles based on reference marks

A data extraction method from data embedding printing images by capturing devices like scanners or mobile cameras has attracted much attention. This method has several problems to be solved, which is different with the digital image watermarking. In the method, consideration for geometrical deformation, especially rotations, in the data extraction process is essential. For the correction, addition of a black frame to an image as a marker has been considered. However it may not be preferable in some case, since the frame may change the impression of the image. This paper proposes new correction method without the remarkable marker. This method can adopt the relationship between the mark in the DFT domain and the rotation of images. By embedding the mark in the DFT domain, the rotational angle can be easily obtained. Related to this new embedding marker, the area in the DCT domain for embedding the information is investigated. Also an image resize technique suitable for this method is developed. From the experimental results, the effectiveness of the proposed method is shown.