Public watermarking algorithm based on the polarity of DCT coefficients

This paper present a novel blind watermarking algorithm based on the AC coefficients distribution properties of an image's DCT transform. This method uses the signs of the DCT coefficients to represent the bit I and 0 respectively. Furthermore, the parameters of this scheme can be calculated since we analyze the round off errors caused by storing a watermarked image. The experiment results show that the algorithm is effective and robust to common image processing operations, such as JPEG lossy compression, cropping, lowpass filter and intensity transform.