This paper proposes a reversible authentication scheme for demosaiced images with the capability to approximately recover original contents of tampered parts. The existing methods protect the marked images to a large extent; however, they cannot detect some intentional modifications, or lack the self-recovery capability of tampered regions. The proposed method uses the most significant bits (MSBs) of sampled components to generate recovery codes, and embeds them into the least significant bits (LSBs) of rebuilt components. The MSBs of rebuilt components are adjusted to reduce the embedding distortion. The authentication codes are generated by hashing the MSBs of adjusted rebuilt components, and are embedded into their LSBs. By analyzing the extracted authentication and recovery codes, the tampered regions can be localized, and the original contents can be approximately recovered. If the marked image is untampered, the original demosaiced image can be exactly reconstructed. Experimental results demonstrate that the proposed method not only provides an excellent marked image quality but also achieves a satisfactory detection and recovery results.

本文提出了一种去马赛克图像的可逆认证方案，能够近似恢复被篡改部分的原始内容。现有方法在很大程度上保护了标记图像。但是，它们无法检测到某些故意的修改，或者缺少篡改区域的自我恢复功能。所提出的方法使用采样组件的最高有效位（MSB）生成恢复码，并将其嵌入到重建组件的最低有效位（LSB）中。调整了重建组件的MSB，以减少嵌入失真。认证代码通过散列调整后的重建组件的MSB生成，并嵌入到它们的LSB中。通过分析提取的身份验证和恢复代码，可以对被篡改的区域进行定位，原始内容可以大致恢复。如果标记的图像不受干扰，则可以精确地重建原始的去马赛克图像。实验结果表明，该方法不仅提供了优异的标记图像质量，而且还获得了令人满意的检测和恢复结果。