Forensics of high-quality JPEG images with color subsampling
Forensics of high-quality JPEG images with color subsampling
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DOI：
10.1109/wifs.2015.7368556
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发表时间：
2015-11
期刊：
影响因子：
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通讯作者：
Matthias Carnein;Pascal Schöttle;Rainer Böhme
中科院分区：
文献类型：
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作者：
Matthias Carnein;Pascal Schöttle;Rainer Böhme
检测先验压缩是图像取证中的一项基本任务，可用于检测数字图像中的伪造。许多方法侧重于灰度图像，并假设压缩质量因子较低，这往往会在图像中留下可见的伪影。然而，在实践中，彩色图像和高质量压缩更为相关和广泛。块收敛被用来估计灰度图像的质量因子为100的JPEG压缩的次数，并已被证明产生了准确的结果[1]。本文将块收敛推广到彩色图像的相关情况，其中色度二次采样和颜色转换使估计变得更加复杂。通过观察宏块在多次重压缩上的块收敛，我们能够对彩色图像产生准确的估计。与灰度图像相比，彩色图像的块收敛通常能够实现类似的精度，并允许检测更多的重新压缩，同时保持从未压缩图像和一次压缩图像之间的良好区别。
Detecting prior compression is an essential task in image forensics and can be used to detect forgery in digital images. Many approaches focus on grayscale images and assume compressions with a low quality factor which often leave visible artifacts in the image. In practice, however, color images and high quality compression are much more relevant and widespread. Block convergence has been proposed to estimate the number of JPEG compressions with quality factor 100 for grayscale images and has been shown to produce accurate results [1]. This paper extends block convergence to the more relevant case of color images where chrominance subsampling and color conversion make the estimation more complex. By observing block convergence for macro-blocks over multiple recompressions we are able to produce accurate estimates for color images. Oftentimes block convergence for color images enables similar accuracy and allows to detect more recompressions compared to grayscale images, while maintaining a good distinction between never and once compressed images.