Abstract: A lossy compression-resisting public watermarking technique was presented. A watermark with visually recognizable pattern was embedded into the host image by modifying the polarity between DC value and low-frequency AC value in each 8 X 8 DCT block, and the watermark was adapted to the image by utilizing the masking characteristics of the human visual system(HVS),watermark extraction processes don't need the original image. The algorithm provides very good results both in terms of image transparency and robustness. The experimental results show that the proposed technique successfully survives lossy compression and common image processing operations.

Key words: Lossy compression, DCT, Digital watermark, Human visual system