用于实现医学图像对比度增强的密文域可逆信息隐藏算法

针对现有密文域医学图像可逆信息隐藏算法存在解密图像视觉质量较低的问题，提出了一种基于差值直方图平移的密文域可逆信息隐藏算法。首先，发送方采用具有同态密文比较性质的加密算法对原始医学图像进行加密，从而保证医学图像的隐私内容不被泄露。然后，嵌入方利用同态性质对接收到的密文图像计算差值直方图，并通过平移差值直方图在密文图像中嵌入信息。为了获得较大的嵌入率，嵌入方可对密文图像进行多轮次信息嵌入。最后，接收方根据拥有的密钥种类对接收到的含有嵌入信息的密文图像进行信息提取、图像解密和图像恢复。实验结果表明，本文算法提升了解密医学图像的视觉质量，同时具有较高的嵌入率和安全性。

Reversible data hiding method in encrypted domain for the contrast enhancement of medical image

Aiming at the problem that the visual quality of the decrypted image is low in the existing reversible data hiding methods for the encrypted medical image, a reversible data hiding method in encrypted domain based on the difference histogram shift was proposed. Firstly, to ensure that the private content of the medical image was not leaked, the sender using an encryption algorithm with the property of homomorphic ciphertext comparison encrypted the original medical image. Then, on the data-hider side, the difference histogram of the received encrypted image was calculated using the homomorphic property, and the secret data was embedded in the encrypted image by shifting the difference histogram. In order to obtain a high embedding rate, the data-hider could conduct multiple rounds of data embedding in the encrypted image. Finally, according to the type of the keys possessed, the receiver could perform data extraction, image decryption and image recovery for the received encrypted image containing embedded data. The experimental results show that the proposed method improves the visual quality of the decrypted medical image, and has high embedding rate and security.