IEEE transactions on image processing : a publication of the IEEE Signal Processing Society最新文献

Blind video quality assessment (VQA) has become an increasingly demanding problem in automatically assessing the quality of ever-growing in-the-wild videos. Although efforts have been made to measure temporal distortions, the core to distinguish between VQA and image quality assessment (IQA), the lack of modeling of how the human visual system (HVS) relates to the temporal quality of videos hinders the precise mapping of predicted temporal scores to the human perception. Inspired by the recent discovery of the temporal straightness law of natural videos in the HVS, this paper intends to model the complex temporal distortions of in-the-wild videos in a simple and uniform representation by describing the geometric properties of videos in the visual perceptual domain. A novel videolet, with perceptual representation embedding of a few consecutive frames, is designed as the basic quality measurement unit to quantify temporal distortions by measuring the angular and linear displacements from the straightness law. By combining the predicted score on each videolet, a perceptually temporal quality evaluator (PTQE) is formed to measure the temporal quality of the entire video. Experimental results demonstrate that the perceptual representation in the HVS is an efficient way of predicting subjective temporal quality. Moreover, when combined with spatial quality metrics, PTQE achieves top performance over popular in-the-wild video datasets. More importantly, PTQE requires no additional information beyond the video being assessed, making it applicable to any dataset without parameter tuning. Additionally, the generalizability of PTQE is evaluated on video frame interpolation tasks, demonstrating its potential to benefit temporal-related enhancement tasks.

Existing multi-view classification algorithms usually assume that all examples have observations on all views, and the data in different views are clean. However, in real-world applications, we are often provided with data that have missing representations or contain noise on some views (i.e., missing or noise views). This may lead to significant performance degeneration, and thus many algorithms are proposed to address the incomplete view or noisy view issues. However, most of existing algorithms deal with the two issues separately, and hence may fail when both missing and noisy views exist. They are also usually not flexible in that the view or feature significance cannot be adaptively identified. Besides, the view missing patterns may vary in the training and test phases, and such difference is often ignored. To remedy these drawbacks, we propose a novel multi-view classification framework that is simultaneously robust to both incomplete and noisy views. This is achieved by integrating early fusion and late fusion in a single framework. Specifically, in our early fusion module, we propose a view-aware transformer to mask the missing views and adaptively explore the relationships between views and target tasks to deal with missing views. Considering that view missing patterns may change from the training to the test phase, we also design single-view classification and category-consistency constraints to reduce the dependence of our model on view-missing patterns. In our late fusion module, we quantify the view uncertainty in an ensemble way to estimate the noise level of that view. Then the uncertainty and prediction logits of different views are integrated to make our model robust to noisy views. The framework is trained in an end-to-end manner. Experimental results on diverse datasets demonstrate the robustness and effectiveness of our model for both incomplete and noisy views. Codes are available at https://github.com/li-yapeng/UVaT.

In this paper, we address a complex but practical scenario in Active Learning (AL) known as open-set AL, where the unlabeled data consists of both in-distribution (ID) and out-of-distribution (OOD) samples. Standard AL methods will fail in this scenario as OOD samples are highly likely to be regarded as uncertain samples, leading to their selection and wasting of the budget. Existing methods focus on selecting the highly likely ID samples, which tend to be easy and less informative. To this end, we introduce two criteria, namely contrastive confidence and historical divergence, which measure the possibility of being ID and the hardness of a sample, respectively. By balancing the two proposed criteria, highly informative ID samples can be selected as much as possible. Furthermore, unlike previous methods that require additional neural networks to detect the OOD samples, we propose a contrastive clustering framework that endows the classifier with the ability to identify the OOD samples and further enhances the network's representation learning. The experimental results demonstrate that the proposed method achieves state-of-the-art performance on several benchmark datasets.