Combining Digital Watermarking and Fingerprinting Techniques to Identify Copyrights for Color Images

Algorithm 2

Watermark embedding.

Input:   A color image H (𝑁×𝑁) and a fingerprint image FP (N/4 × N/4).

Output:   A watermarked image (𝑁×𝑁).

Apply DWT to the R and B channels of H to obtain the four embedding blocks 𝐼₁,…,𝐼₄

For each coefficient c of the 𝐼₁--𝐼₄ blocks and the corresponding pixel of FP

    Compute the sign, 𝑆, and (𝑟₀, 𝑟₁) by (3), (4), and (5), respectively

    Compute the C_Low and C_High by (6) if watermark bit is 0, or (7) if otherwise

    Adjust the coefficient to 𝑐^′ by (8)

End For

Perform inverse DWT to produce the watermarked image