A secure DWT-based dual watermarking scheme for image authentication and copyright protection

Digital watermarking mechanisms have become an essential tool for guaranteeing copyright protection and content authentication. However, most state-of-the-art works focus on providing only one of these services. In this paper, a dual watermarking scheme for image authentication and copyright protection is introduced. The proposed scheme simultaneously embeds two watermarks in the host image by exploiting the discrete wavelet transform (DWT). A fragile watermark and a robust watermark are embedded into frequency domain by modifying DWT coefficients of high-frequency sub-bands. To improve the scheme security, host image undergoes a chaotic transformation while robust watermark is obtained by using a particular visual cryptography technique. The proposed scheme provides satisfactory watermark imperceptibility levels, achieving PSNR values above 49dB when a small watermark is used and above 40dB when a larger watermark is embedded. Several image processing attacks are applied to evaluate the watermark robustness, obtaining normal correlation coefficient values near to 1 against most attacks. Finally, an authentication accuracy near to 1 is achieved when marked images undergo tampering attacks. The obtained results show that proposed scheme achieves competitive results in terms of imperceptibility and outperforms similar state-of-the-art dual watermarking methods in terms of watermark robustness and authentication accuracy.