Development of adaptive digital image watermarking techniques in color image using fourier series expansion

摘要

Digital watermarking is to embed imperceptable mark into image, video, audio and text data to prevent the illegal copy of multimedia data, arbitrary modification, and also illegal sales of the copies wihtout agreement of copyright ownership. In this research, original RGB image is converted to YIQ image and transformed only Y(Luminance) component of YIQ using DCT transform and the Foruier series expansion of these DCT coefficient is conducted. In order to embed the imperceptible and robust watermark, we generate M x N random sequences of watermark position and harmonics of sine and cosine function. We calculate the Foruier coefficient of sine and cosine function which have the complete set of orthogonal basis funciton, and modify these coefficients. In the experiment, we can show robustness with respect to image distortion such as JPEG compression, blurring and adding uniform noise. The correlation coefficient was in the range from 0.0755 to 0.9792.