Data Embedding and Extraction Method for Printed Images by Log Polar Mapping
Data extraction methods from data embedding printed images by capturing devices like scanners or mobile cameras have attracted much attention. In this technique, consideration for geometrical deformation, especially rotation and scaling, in the data extraction process is essential. This paper proposes a new correction algorithm without remarkable markers. This method exploits the log polar mapping (LPM) to detect and correct the distortion. The proposed method estimates the rotational angle and scaling factor from the amount of shift in the LPM domain. Therefore no data embedding or adding for correcting the deformation is required and the data embedded image with high quality is obtained. An image clipping technique suitable for the proposed method is also developed. From the experimental results, the effectiveness of the proposed method is shown.
KeywordsDiscrete Fourier Transform Digital Watermark Reference Mark Orthogonal Coordinate System Rotation Correction
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