Research on a Digital Watermarking Algorithm for Color Image Based on Dual-Tree Complex Wavelet Transform (DTCWT)

This paper proposes a digital watermarking algorithm for color image based on Dual-Tree Complex Wavelet Transform (DTCWT). It decomposes the color watermark image M in the RGB color space into three channels, i.e. R, G and B, and then applies Arnold transform on them respectively. It then applies DCT (Discrete Cosine Transform) and DFT (Discrete Fourier Transform) on the scrambled watermarks in the frequency domain. The algorithm applies Dual-Tree Complex Wavelet Transform (DTCWT) on the color carrier image, and uses the third-level low-frequency sub-bands of its real part as the embedded sub-bands. It then embeds all the above-mentioned watermarks into these sub-bands. Finally, it applies inverse Dual-Tree Complex Wavelet Transform on the color carrier image embedded with the color watermark to embed the color watermark into it. Watermark extraction is the inverse process of watermark embedding. Experimental results show that this algorithm features high imperceptibility and robustness.