"Adaptive Quantization of Wavelet Packet Coefficients for Embedding and Extraction of Digital Watermarks ":
Abstract—In this paper, a robust digital image watermarking 
approach of  embedding and extraction of digital watermarks using 
adaptive quantization of wavelet packet coefficients was proposed. 
The original image is decomposed by discrete wavelet packet 
transform and the dominant wavelet coefficients are selected for 
watermark embedding from each sub-band except the lowest 
frequency one. Then, each watermark bit is adaptively embedded 
with different strength into the  selected wavelet packet coefficients 
based on the odd or even value after quantization. 
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