Robust High Frequency DCT Domain Image Watermarking with Adjusted Mean Adaptive Threshold Method

The watermark embedding at low frequencies causes more distortion or less visual quality in the image compared to the watermark embedding at high frequencies. On the other hand, if a watermark is embedded at low frequencies, it can be extracted with a lower bit error rate or greater robustness than if the same watermark is embedded at high frequencies. In this paper, watermark bits are inserted in the DCT high frequency components using the proposed adjusted mean adaptive threshold method. To achieve both robustness and visual quality in the watermarked image, we introduce a parameter, denoted as b, which allows us to adjust the mean adaptive threshold value. The selection of this parameter is crucial as it determines the optimal balance between robustness and visual quality. Through simulation experiments, the appropriate value of b is determined for different attacks such as JPEG quantization, Gaussian noise, and averaging filter applied to high frequency watermarking. By using the minimum appropriate values of "b" equal to ۰.۵, ۲.۵, and ۲ for JPEG quantization, Gaussian noise, and averaging filter attacks, respectively, the high frequency watermarking at coordinates (۷,۸) and (۸,۷) exhibit better visual quality and robustness compared to the low frequency watermarking of reference method, in general.

کلیدواژه ها:

DCT Domain Image Watermarking ، Robust Watermarking ، Attack