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In this article, we aim to detect the double compression of MPEG-4, a universal video codec that is built into surveillance systems and shooting devices. Double compression is accompanied by various types of video manipulation, and its traces can be exploited to determine whether a video is a forgery. To this end, we present a neural network-based approach with discriminant features for capturing peculiar artifacts in the discrete cosine transform (DCT) domain caused by double MPEG-4 compression. By analyzing the intra-coding process of MPEG-4, which performs block-DCT-based quantization, we exploit multiple DCT histograms as features to focus on the statistical properties of DCT coefficients on multiresolution blocks. Furthermore, we improve detection performance using a vectorized feature of the quantization table on dense layers as auxiliary information. Compared with neural network-based approaches suitable for exploring subtle manipulations, the experimental results reveal that this work achieves high performance., Accepted to IEEE MultiMedia

Image forensics comprises the analyses and classifications of manipulations that have been applied to images. The ability to classify various manipulations that have been employed in the process of forgery is essential. Techniques to identify multiple manipulations applied to uncompressed images have been reported thus far, but the forensic approach for JPEG images compressed with various qualities has not been proposed. In this paper, we propose the manipulation classification network (MCNet) to exploit multi-domain features of the spatial, frequency, and compression domains. The proposed MCNet learns several forensic features for each domain through a multi-stream structure and distinguishes manipulations by comprehensively analyzing the fused features. Our work jointly considers visual artifacts caused by image manipulations and compression artifacts due to JPEG compression; therefore, rich forensic features can be explored and learned in the training phase. To enable forgery analysis in the real-world environment, data were generated based on twenty types of manipulation algorithms and various compression parameters. To demonstrate the effectiveness of the proposed MCNet, extensive experiments were conducted using state-of-the-art baselines. Compared to these baselines, our proposed method outperforms in terms of multi-class manipulation classification. In addition, we experimentally proved that the fine-tuned model based on the multi-class manipulation task was effective for different forensic tasks such as DeepFake detection or integrity authentication of JPEG images.