A new method for color image watermarking based on combination of DCT and PCA

In the digital watermarking with DCT method, the watermark is located within a range of DCT coefficients of the cover image. In this paper a new method is proposed by using a combination of the DCT and PCA transform in order to use the low-frequency band for the color image. First, the digital color image is transformed into YCbCr from RGB color space and the luminance (Y) component is divided into non-overlapping blocks and the low-band coefficients of each block are placed in the matrix data, the PCA transform will be applied to it. The watermark is embedded in the first component of the PCA. The proposed method is compared to other DCT methods. Our method is robust and keeps the quality of the cover image, also increases capacity of the watermarking.