An Image Authentication Scheme Based on Correlation

This paper proposes a watermarking algorithm based on correlation to authenticate image content. The original image is converted to YIQ space first, then subdivided into 8× 8 non-overlapping blocks. DCT transform is executed on each block. The watermark sequence is derived from certain low frequency coefficients. It is hided into the middle frequency DCT coefficients of another pseudo-randomly selected block with different embedding strength according to the pre-calculated correlation. The content authentication is implemented through correlation calculation between the low frequency coefficients and the corresponding middle frequency coefficients. Experiment shows that the algorithm is robust to JPEG compression, and it is sensitive to malicious tampering. Comparison with other similar watermarking algorithms in DCT domain is also taken to verify our scheme. The scheme is secure and suitable to be used in image content authentication.