Colour-Adaptive Digital Image Watermarking Technique

Copyright protection and owner authentication have become necessary due to the circulation of large number of documents, images, audios, and videos through the internet. Manipulations and duplications in multimedia files and documents are very easy due to advancement in the signal and image processing algorithms. Therefore, it is very much important to devise watermarking techniques that are robust against geometrical distortions and collision attacks. In this paper, we proposed an adaptive digital image watermarking technique through colour features and Arnold transform in wavelet domain. An attempt has been made to adaptively transform the watermark image into a set of textures that visually match the colour of the input host image since colour features are invariant with respect to translation and rotation of the image. We first separate the three colours R, G, and B of the host and watermark image. Next, we decomposed the separated images using wavelet transform into sub-bands. Finally, low-frequency sub-band of the watermark image is embedded into low-frequency sub-band of the host image using Arnold transform. Experimental results on multiple host images and under various attacks using PSNR and correlation coefficient, clearly demonstrates that the proposed algorithm is robust and can be applied in colour image watermarking.