A gray image watermarking algorithm based on DCT

A robust invisible image watermarking algorithm, which embeds a gray image watermarking in the host image, is put forward in this paper. It overcomes the binary watermark´s faults, and can embeds higher b it rate in the host image based on blockwise DCT. The gray image watermark is embedded in the host image by altering the chosen DCT medium frequency coefficients, which is easy to be implemented. The experimental results confirm that the proposed algorithm successfully withstands most of the common attracts, including noise interference, cropping, and image compression.