Method of Embedding and Extracting Watermark Data

A data extracting method for extracting watermark data from a captured image in which the watermark data are an embedded image, the data extracting method comprising the steps of:

• generating a correction image from a photographed image;
• monochromating the correction image to maximize an expression of noise inherent in the correction image to create a monochromated corrected image;
• generating a second two-dimensional result matrix indicating whether a noise-based image is comprised in the photographed image by performing a frequency domain process of comparing the photographed image with the noise-based image;
• transforming the second two-dimensional result matrix into a spatial domain to generate a second reference image;
• determining a reference point that is an extraction position of the watermark data in the captured image using the second reference image, and
• extracting the watermark data from a reference point of the photographed image with reference to the noise-based image;
• wherein, the step of generating the second two-dimensional result matrix comprises the step of generating a second result matrix indicating whether the noise-based image is comprised in the corrected image by performing a process in a frequency domain that compares the monochromated corrected image with a noise-based image;
• wherein, the step of determining the extraction position of the watermark data comprises the step of determining a reference point that is an extraction position of the watermark data in the monochromated corrected image;
• and
• wherein, the step of extracting the watermark data comprises the step of extracting the watermark data from the monochromated corrected image.