Research on Adaptive Digital Watermarking Based on Spread Spectrum

摘要

In this paper, the direct-sequence spread-spectrum technique is introduced to spread watermark signal. Then by utilizing a just noticed difference threshold in spatial domain based on visual masking effect of human visual system, watermarks strength and the embedded locations can be controlled in image adaptively. It was shown with experiments that the digital watermark not only can guarantee the transparency, but also has good robustness to JPEG compression, median filter, sub-sampling etc.