Existing scene text detectors generally focus on accu-rately detecting single-level (i.e., word-level, line-level, or paragraph-level) text entities without exploring the relationships among different levels of text entities. To comprehensively understand scene texts, detecting multi-level texts while exploring their contextual information is criti-cal. To this end, we propose a unified framework (dubbed LayoutFormer) for hierarchical text detection, which simultaneously conducts multi-level text detection and predicts the geometric layouts for promoting scene text understanding. In LayoutFormer, WordDecoder, LineDecoder, and Pa- raDecoder are proposed to be responsible for word-level text prediction, line-level text prediction, and paragraph- level text prediction, respectively. Meanwhile, WordDe-coder and ParaDecoder adaptively learn word-line and line-paragraph relationships, respectively. In addition, we propose a Prior Location Sampler to be used on multi-scale features to adaptively select a few representative foreground features for updating text queries. It can improve hierar- chical detection performance while significantly reducing the computational cost. Comprehensive experiments verify that our method achieves state-of-the-art performance on single-level and hierarchical text detection.

Benefiting from attention mechanisms, query-based detectors have a strong model capacity. They predict classification and regression by utilizing their shared queries and features in the decoder. Inter-task biases cause multi-directional gradients that disturb each other to limit model optimization. In this work, we introduce an attention decoupling (AD) for query-based detectors to explicitly align multi-task features. Specifically, AD consists of a Dense-to-Sparse Query Generator (DSQG) and a Split Cross-Attention (SCA), enabling query and feature decoupling respectively in decoding phase. Then, we propose a task consistency loss (TCL) which integrates a novel task alignment metric to classification loss to further improve task consistency across multiple decoding stages. Thus, AD effectively mitigates query-based detectors’ task misalignment problem and inspires subsequent multi-task paradigms. Moreover, extensive experiments on COCO dataset demonstrate that the proposed AD can enhance a variety of representative detectors. Remarkably, AD-DINO achieves the state-of-the-art performance.

Label assignment (LA) is one of the essential phases in the object detection paradigm and aims to classify samples as foreground or background. Current LA strategies generally discriminate samples by explicit thresholds and then calculate weighted losses based on their significances. However, existing methods mostly neglect to consider the importance of samples comprehensively due to the uneven distribution of objects and the limitations of detector structures. In this paper, we propose a hierarchical equalization loss (HEL) by reconsidering the underlying factors affecting sample weights. First, we mitigate sample imbalance at three progressive levels. (1) Task level. We propose task-reconciled weights (TRW) to overcome the effects caused by inter-task inconsistencies (i.e., the inherent differences of classification and localization). (2) Instance level. We propose instance-aware normalization (IAN) for reconstructing the distribution of sample weights within an instance to suppress environmental noise. (3) Pyramid level. We propose hierarchical modulation (HM) to alleviate the unbalanced distribution of multi-scale objects on feature pyramids. Then, we stack the above three mechanisms and formulate the effective weighted loss. Moreover, we propose a staggered candidate bag construction (SCBC) mechanism to further improve the robustness of our method. Without adding any extra overhead, HEL can improve the performance of representative detectors by an impressive margin. Equipped with HEL, a single “ResNet-50+FPN+Head” detector can achieve a performance of 41.9 AP on COCO under 1× schedule, outperforming other existing LA methods. Extensive experiments conducted on multiple backbones and datasets demonstrate the effectiveness of our method.

Multi-scale object detection in natural scenes is still challenging. To enhance the multi-scale perception capability, some algorithms combine the lower-level and higher-level information via multi-scale feature fusion strategies. However, the inherent spatial properties among instances and relations between foreground and background are ignored. In addition, the human-defined “center-based” regression quality evaluation strategy, predicting a high-to-low score based on a linear relationship with the distance to the center of ground-truth box, is not robust to scale-variant objects. In this work, we propose a Depth-Guided Progressive Network (DGPNet) for multi-scale object detection. Specifically, besides the prediction of classification and localization, the depth is estimated and used to guide the image features in a weighted manner to obtain a better spatial representation. Therefore, depth estimation and 2D object detection are simultaneously learned via a unified network, where the depth features are merged as auxiliary information into the detection branch to enhance the discrimination among multi-scale objects. Moreover, to overcome the difficulty of empirically fitting the localization quality function, high-quality predicted boxes on scale-variant objects are more adaptively obtained by an IoU-aware progressive sampling strategy. We divide the sampling process into two stages, i.e., “statistical-aware” and “IoU-aware”. The former selects thresholds for positive samples based on statistical characteristics of multi-scale instances, and the latter further selects high-quality samples by IoU on the basis of the former. Therefore, the final ranking scores better reflect the quality of localization. Experiments verify that our method outperforms state-of-the-art methods on the KINS and Cityscapes dataset.

Vehicle and license plate detection plays an important role in intelligent transportation systems and is still a challenging task in real applications, such as on-road scenarios. Recently, Convolutional Neural Network (CNN)-based detectors achieve the state-of-the-art performance. However, it is difficult to efficiently detect the vehicle and license plate simultaneously in most cases. With a single network, the vehicle can affect the detection of the license plate due to the inclusion relation. In this paper, we propose an end-to-end deep neural network for detecting the vehicle and the license plate simultaneously in a given image, where two separate branches with different convolutional layers are designed for vehicle detection and license plate detection, respectively. In consideration of the license plate's small size and fairly obvious features as well as the vehicle's various size and rather complex features, the license plates are detected with low-level features and the vehicles are localized with multi-level features in corresponding convolutional layers. Moreover, a task-specific anchor design strategy is employed to obtain better predictions. Besides, the attention mechanisms and feature-fusion strategies are utilized to improve the detection performance of small-scale objects. A variety of experiments on real datasets and public datasets verify that our proposed method has fairly high accuracy and efficiency.

Hash-based message authentication code (HMAC) is widely used in authentication and message integrity. As a Chinese hash algorithm, the SM3 algorithm is gradually winning domestic market value in China. The side channel security of HMAC based on SM3 (HMAC-SM3) is still to be evaluated, especially in hardware implementation, where only intermediate values stored in registers have apparent Hamming distance leakage. In addition, the algorithm structure of SM3 determines the difficulty in HMAC-SM3 side channel analysis. In this paper, a skillful bit-wise chosen-plaintext correlation power attack procedure is proposed for HMAC-SM3 hardware implementation. Real attack experiments on a field programmable gate array (FPGA) board have been performed. Experimental results show that we can recover the key from the hypothesis space of 2 256 based on the proposed procedure.