A robust image watermarking arithmetic with scaling compatible in DCT domain

By analyzing the relationship between the fore-scaling and post-scaling of the images´ DC coefficients, this paper proposes a robust image watermarking arithmetic with scaling compatible in DCT domain. Hung together with the JPEG encoding course, this method embeds the watermark information into the DC coefficients after the discrete cosine transform and abstracts the corresponding information from the DC coefficients by dividing a content value at the detecting course. Experiment shows this arithmetic can detect the watermark well after the scaling operation, and it has a high detecting ratio in the normal image processing.