Detecting double Joint Photographic Experts Group (JPEG) compression for color images is vital in the field of image forensics. In previous researches, there have been various approaches to detecting double JPEG compression with different quantization matrices. However, the detection of double JPEG color images with the same quantization matrix is still a challenging task. An effective detection approach to extract features is proposed in this paper by combining traditional analysis with Convolutional Neural Networks (CNN). On the one hand, the number of nonzero pixels and the sum of pixel values of color space conversion error are provided with 12-dimensional features through experiments. On the other hand, the rounding error, the truncation error and the quantization coefficient matrix are used to generate a total of 128-dimensional features via a specially designed CNN. In such a CNN, convolutional layers with fixed kernel of $1\times 1$ and Dropout layers are adopted to prevent overfitting of the model, and an average pooling layer is used to extract local characteristics. In this approach, the Support Vector Machine (SVM) classifier is applied to distinguish whether a given color image is primarily or secondarily compressed. The approach is also suitable for the case when customized needs are considered. The experimental results show that the proposed approach is more effective than some existing ones when the compression quality factors are low.

Building an effective sequential recommendation system is still a challenging task due to limited interactions among users and items. Recent work has shown the effectiveness of incorporating textual or visual information into sequential recommendation to alleviate the data sparse problem. The data sparse problem now is attracting a lot of attention in both industry and academic community. However, considering interactions among modalities on a sequential scenario is an interesting yet challenging task because of multimodal heterogeneity. In this paper, we introduce a novel recommendation approach of considering both textual and visual information, namely Multimodal Interactive Network (MIN). The advantage of MIN lies in designing a learning framework to leverage the interactions among modalities from both the item level and the sequence level for building an efficient system. Firstly, an item-wise interactive layer based on the encoder-decoder mechanism is utilized to model the item-level interactions among modalities to select the informative information. Secondly, a sequence interactive layer based on the attention strategy is designed to capture the sequence-level preference of each modality. MIN seamlessly incorporates interactions among modalities from both the item level and the sequence level for sequential recommendation. It is the first time that interactions in each modality have been explicitly discussed and utilized in sequential recommenders. Experimental results on four real-world datasets show that our approach can significantly outperform all the baselines in sequential recommendation task.