Watermarking Method Using Concatenated Code for Scaling and Rotation Attacks

We proposed a watermarking method using a concatenated code and evaluated the method on the basis of IHC evaluation criteria. The criteria include JPEG compression, clipping, scaling, and rotation as attacks. For the robustness of messages, we introduced concatenated code, since it has a high error corrective ability to decode messages against JPEG compression. When a region is cropped from a stego-image, the position of watermarks might be unclear. Therefore, markers or synchronization codes were embedded into the stego-image. Since scaling causes pixel loss, and rotation causes distortion, watermarks were embedded into minified images. Quantization index modulation was used for embedding and extracting the watermarks without the original images. As a result, our method was evaluated on the basis of highest image quality and could achieve an average peak signal-to-noise ratio of 36.250 dB. Moreover, our method was evaluated on the basis of highest tolerance and could achieve an average compression ratio of 2.633% without errors.