METHOD FOR GENERATING DIGITAL WATERMARK AND DETECTING DIGITAL WATERMARK

摘要

A method for generating and detecting a digital watermark is provided to improve the inaudibility of a watermark by inserting the watermark through distribution value correction of a band signal group and to improve robustness by inserting the watermark using wavelet coefficient of the band signal group corresponding low frequency reference coefficient greater than threshold. Digital signals are divided into a plurality of frame signals(S200). The frame signals are converted into the predetermined number of band signal groups through wavelet transformation(S210). A band signal group determined as a conversion target is normalized statistically(S220). A plurality of predetermined wavelet coefficients of the conversion target band signal groups are selected corresponding to the wavelet standard coefficients of a low frequency band signal group having a greater value than the threshold value on the basis of standard deviation and the threshold value, and divided into two groups according to a sign of the low frequency standard coefficient(S230). A watermark is inserted by correcting the distribution values of the two groups(S240). The conversion target band signal group is normalized reversely, and a plurality of frame signals are created by converting the predetermined number of band signal group(S250). Each frame signal is merged, and digital signals are generated(S260).