A quantization-based semi-fragile watermarking scheme for image content authentication

This paper presents a novel semi-fragile watermarking scheme for image content authentication with tampering localization. The proposed scheme uses a non-traditional quantization method to modify one chosen approximation coefficient of each non-overlapping block to ensure its robustness against incidental attacks and fragileness against malicious attacks. The image content authentication starts with extracting watermark using the parity of quantization results from the probe image, where the round operation is used to ensure the semi-fragile property. It then constructs a binary error map and computes two authentication measures with M1 measuring the overall similarity between extracted and embedded watermarks and M2 measuring the overall clustering level of tampered error pixels. These two measures are further integrated to confirm the image content and localize the possible tampered areas. Our experimental results show that our scheme outperforms four peer schemes and is capable of identifying intentional tampering and incidental modification, and localizing tampered regions.

Research highlights
► Apply a non-traditional quantization method to embed watermark.
► Define authentication measures to detect the authenticity of the probe image.
► Use an error map and authentication measures to localize possible tampered areas.
► Apply randomness strategies to increase the security of the proposed system.