Blind curvelet watermarking method for high‐quality images

The proposed method is a watermarking method for high‐quality images that achieves high invisibility and good robustness using a curvelet domain. Recently, there has been a demand for a watermarking technique that does not impair image quality, as interest in high‐quality images has increased. To meet this demand, the authors adopted a method of minimising the watermark‐embedding energy by using the multi‐directional decomposition technique, curvelet transformation. However, if a watermark is inserted into the curvelet domain with the watermarking technique of the conventional domains, it is distorted during the forward and inverse curvelet transform. To solve this problem, they designed a watermarking method by considering the characteristics of the curvelet filter. By minimising the watermark distortion caused by the curvelet transform, high robustness is achieved with small watermarking energy. The proposed method shows very good invisibility and is difficult to distinguish the original. In terms of robustness, the correlation value increased by >80% and BER decreased by >20% compared with previous methods.