METHOD AND APPARATUS FOR DIGITAL WATERMARKING

摘要

PURPOSE: A method and an apparatus for digital watermarking are provided to prevent a watermark signal embedded into audio signal data from being removed by an unauthorized person, and to minimize the distortion of original data. CONSTITUTION: The method for digital watermarking comprises the steps of: fourier transforming audio signal data to generate first and second component data of a frequency area; wavelet transforming an absolute value of the first component data to generate a first spectrum coefficient; discrete cosine transforming a watermark signal to form a second spectrum coefficient; combining the first and the second spectrum coefficient; and inverse wavelet transforming the coefficient thus combined. The apparatus for digital watermarking comprises: a fourier transformer(10) for fourier transforming audio signal data to generate amplitude component data and phase component data; a wavelet transformer(13) for wavelet transforming the absolute value of the amplitude component data to generate the first spectrum coefficient; a discrete cosine transformer(14) for discrete cosine transforming the watermark signal to form the second spectrum coefficient; an adder(30) for combining the first and the second spectrum coefficient; and an inverse wavelet transformer(16) for inverse wavelet transforming the coefficient thus combined.