Non blind image watermarking based on similarity in contourlet domain

This paper presents a non blind watermarking technique for gray scale images in contourlet domain. It uses the similarity based approach to create an effective watermarking system. In the proposed scheme host image is decomposed in contourlet domain upto four hierarchical levels. The watermark logo image and the directional subband of host image are divided into image blocks of size 8×8. The similarity coefficients are calculated between watermark image block and subband image block. The watermark image block is embedded into the directional subband block with best similarity. The PSNR value obtained using the proposed method is 46.76 dB. To test the robustness of the proposed method general geometric attacks such as salt & pepper noise, poisson noise, speckle noise, cropping attacks and JPEG compression attacks were applied. The experimental result shows that the proposed method has higher robustness for cropping and JPEG compression attacks.