Image content authentication system based on semi-fragile watermarking

In this paper, an image content authentication algorithm based on semi-fragile watermarking is proposed. In the proposed approach, the robust digital signature which is extracted from the image is embedded into the image as a watermark signal. The embedding process is performed using Vector Quantization method in the Discrete Wavelet Transform domain, while the watermark extraction process is performed using a blind scheme, where the original image is not required. The proposed algorithm is applied to gray-scale and color images. The experimental results show that the proposed technique detects the photomontage region of the images a false positive error of about 10%, while the technique tolerates any modification which preserves image contents such as: JPEG compression and noise contamination. The proposed algorithm is compared with another authentication method to show desirable performance of the proposed one.