Digital Image Watermarking Algorithm Based on Wavelet Transform

A robust digital image watermarking algorithm in wavelet transform domain is proposed. In the algorithm the original gray image is decomposed into some coefficients in different spatial and frequency sub-bands. Using the characteristic that father node is associated with its child nodes, watermark is embedded in the father nodes by establishing a relationship between father node and the average value of its child nodes. The original carrier image is not needed in the process of watermark extraction. The experimental results show that the algorithm is invisible and robust against common image processing and attacks.