Robust Watermarking by SVD of Watermark Embedded in DKT-DCT and DCT Wavelet Column Transform of Host Image

Watermarking in wavelet domain and with SVD is popular due to its robustness. In this paper a watermarking technique using DCT wavelet and hybrid DKT-DCT wavelet along with SVD is proposed. Wavelet transform is applied on host and SVD is applied on watermark. Few singular values of watermark are embedded in mid frequency band of host. Scaling of singular values is adaptively done for each channel (Red, green and blue) using the highest transform coefficient from selected mid frequency band and first singular value of corresponding channel of watermark. Singular values of watermark are placed at the index positions of closely matching transform coefficients. This along with the adaptive selection of scaling factor adds to the robustness of watermarking technique. Performance of the proposed technique is evaluated against image processing attacks like cropping, compression using orthogonal transforms, noise addition, histogram equalization and resizing. Performance for DCT wavelet and DKT-DCT wavelet is compared and in many of the attacks DCT wavelet is found to be better than DKT-DCT wavelet.