Color image digital watermarking using discrete quaternion cosine-transform

A new method for color image watermarking using discrete quaternion cosine-transform(DQCT) is proposed.The color image can be processed as a whole rather than as separated color components in three channels.The watermark image can be embedded in the DQCT domain of the host color image.Experimental results show that this method has good resistance to JPEG compression and is robust against Gaussian noise,salt pepper noise and image scaling attack.