A Novel Comprehensive Watermarking Scheme for Color Images

Algorithm 1

Embedding robust watermark .

(1)	Step 1: apply the one-level shearlet transform on the R layer of the color image, thus to obtain a low pass subband .
(2)  Step 2: apply the DWT transformation to .
(3)  Step 3: divide the low-frequency area (LL) into nonoverlapping blocks of 8 × 8, and apply DCT on each block.
(4)  Step 4: select the middle frequency of the DCT coefficients from one block [16], which consists of two matrices, and . The construction of matrices with middle frequency is given in Figure 3.
(5)	Step 5: use SVD to decompose and to get singular value matrices. The singular value matrices of and are and , respectively.
(6)  Step 6: use the following equations to embed the watermark [16]: and .
(7)	Step 7: repeat steps 4–6 until all watermarks are embedded, and then perform a reverse transformation to get a watermarked layer.