Recent study has found out that after multiple times of recompression, the DCT coefficients of JPEG image can form an embedding domain that is robust to recompression, which is called transport channel matching (TCM) method. Because the cost function of the adaptive steganography does not consider the impact of modification on the robustness, the modified DCT coefficients of the stego image after TCM will change after recompression. To reduce the number of changed coefficients after recompression, this paper proposes a robust steganography algorithm which dynamically updates the robustness cost of every DCT coefficient. The robustness cost proposed is calculated by testing whether the modified DCT coefficient can resist recompression in every step of STC embedding process. By adding robustness cost to the distortion cost and using the framework of STC embedding algorithm to embed the message, the stego images have good performance both in robustness and security. The experimental results show that the proposed algorithm can significantly enhance the robustness of stego images, and the embedded messages could be extracted correctly at almost all cases when recompressing with a lower quality factor and recompression process is known to the user of proposed algorithm.
翻译:最近的研究发现,经过多次再压缩后,JPEG图像的DCT系数可以形成一个内嵌域域,这个内嵌域对于再压缩来说是强大的,称为运输频道匹配(TCM)方法。由于适应性色谱法的成本功能没有考虑到修改对稳健性的影响,因此在TCM之后修改的stego图像的DCT系数在再压缩后会发生变化。为了减少再压缩后系数的变化数量,本文件建议了一种强有力的Stegraphy算法,以动态方式更新每个DCT系数的稳健性成本。提议的坚固性成本是通过测试修改后的DCT系数是否能在STC嵌入过程的每一个步骤中抵制再压缩来计算的。通过在扭曲成本中加上稳健性成本,并利用STC嵌入算法框架来嵌入电文,Stego图像在稳健性和安全性两方面都表现良好。实验结果表明,拟议的算法可以大大增强Stego图像的稳健性,而嵌入的信息可以在几乎所有情况下,在已知的用户质量系数和重新压缩过程中正确提取。