In this paper, we evaluate the degradation of an image due to the implementation of a watermark in the frequency domain of the image. As a result, a watermarking method, which minimizes the impact of the watermark implementation on the overall quality of an image, is developed. The watermark is embedded in magnitudes of the Fourier transform. A peak signal-to-noise ratio is used to evaluate quality degradation. The obtained results were used to develop a watermarking strategy that chooses the optimal radius of the implementation to minimize quality degradation. The robustness of the proposed method was evaluated on the dataset of 1000 images. Detection rates and receiver operating characteristic performance showed considerable robustness against the print-scan process, print-cam process, amplitude modulated, halftoning, and attacks from the StirMark benchmark software.

In this paper we developed a steganographic method for image protection on Facebook social network. The method hides additional information such as a logo or serial number. Uploading the images on the social network has induced image degradation on the original images. Based on the analysis of this attack we developed a method based on the discrete cosine transform - DCT where additional information is hidden by modifying the coefficients in the cosine domain. The method was evaluated and it is shown that bit error rate (BER) for different attacks was below 1%.