一种改进的DCT变换图像AC系数恢复方法DC
An Improved DC Recovery Method from AC Coefficients of DCT-Transformed Images
摘要：
受Uehara等人[1]工作的启发，本文研究了一种从DCT变换图像的AC系数中恢复DC系数的改进方法，并将其应用于选择性多媒体加密的密码分析中。所提出的下/溢流速率最小化（FRM）方法采用优化过程来获得未知DC系数的统计上更准确的估计，从而实现更好的恢复性能。基于200幅测试图像的实验结果表明，本文提出的DC恢复方法在PSNR值和几种最先进的客观图像质量评价（IQA）指标（如SSIM和MS-SSIM）方面显著提高了大多数恢复图像的质量。
英文摘要：
Motivated by the work of Uehara et al. [1], an improved method to recover DC coefficients from AC coefficients of DCT-transformed images is investigated in this work, which finds applications in cryptanalysis of selective multimedia encryption. The proposed under/over-flow rate minimization (FRM) method employs an optimization process to get a statistically more accurate estimation of unknown DC coefficients, thus achieving a better recovery performance. It was shown by experimental results based on 200 test images that the proposed DC recovery method significantly improves the quality of most recovered images in terms of the PSNR values and several state-of-the-art objective image quality assessment (IQA) metrics such as SSIM and MS-SSIM.
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