Abstract: With the actuality that the colorspaces used by the digital media, it converts RGB image and watermark into vectors of the colorspace that the digital media uses, transforms these vectors by two dimension DCT and appends watermark coefficients to related RGB image coefficients with controllable intension and composes RGB image containing watermark, composes those coefficients being appended to a RGB key image. The main contributions of the paper are that it uses RGB image and RGB watermark, it is to be the same with all the colorspaces that popular digital media used, it enhances real time response ability of the algorithm by avoiding sortting and reallocation DCT coefficients. Experimentations show that the algorithm is robust to several signal processing techniques, including cut, JPEG lose compression, stretching, addition of noise, faint and sharpen operations etc.

Key words: Key image, RGB watermark, RGB image, Colorspace, Discrete cosine transformation(DCT)

摘要： 按照流行媒体使用的颜色空间，将真彩水印的系数按照一定的强度附加在真彩图像对应的中低频系数上，使真彩图像被附加的系数合成真彩密钥图。算法的主要贡献在于使用了真彩水印和图像，适用于常见媒体使用的彩色空间，避免了DCT系数的排序与重定位。试验表明，算法具有较强的抗剪切、JPEG有损压缩、缩放、噪声、模糊和锐化等能力。

关键词: 密钥图, 真彩水印, 真彩图像, 颜色空间, 离散余弦变换