Image content dependent semi-fragile watermarking with localized tamper detection

TL;DR

This paper introduces a semi-fragile watermarking method that depends on image content and local dependencies, enabling precise tamper detection and classification with high accuracy, robustness, and improved security over existing techniques.

Contribution

The proposed method generates content-dependent watermarks with inter-block dependencies and automates tamper detection and classification, addressing vulnerabilities of prior semi-fragile watermarking approaches.

Findings

High classification accuracy of 97.97%

Robust against JPEG compression

Competitive with state-of-the-art methods

Abstract

Content-independent watermarks and block-wise independency can be considered as vulnerabilities in semi-fragile watermarking methods. In this paper to achieve the objectives of semi-fragile watermarking techniques, a method is proposed to not have the mentioned shortcomings. In the proposed method, the watermark is generated by relying on image content and a key. Furthermore, the embedding scheme causes the watermarked blocks to become dependent on each other, using a key. In the embedding phase, the image is partitioned into non-overlapping blocks. In order to detect and separate the different types of attacks more precisely, the proposed method embeds three copies of each watermark bit into LWT coefficients of each 4x4 block. In the authentication phase, by voting between the extracted bits the error maps are created; these maps indicate image authenticity and reveal the modified regions. Also, in order to automate the authentication, the images are classified into four categories using seven features. Classification accuracy in the experiments is 97.97 percent. It is noted that our experiments demonstrate that the proposed method is robust against JPEG compression and is competitive with a state-of-the-art semi-fragile watermarking method, in terms of robustness and semi-fragility.