Deep neural networks (DNNs) have shown great potential in no-reference image quality assessment (NR-IQA). However, the annotation of NR-IQA is labor-intensive and time-consuming, which severely limits its application, especially for authentic images. To relieve the dependence on quality annotation, some works have applied unsupervised domain adaptation (UDA) to NR-IQA. However, the above methods ignore the fact that the alignment space used in classification is sub-optimal, since the space is not elaborately designed for perception. To solve this challenge, we propose an effective perception-oriented unsupervised domain adaptation methodStyleAM(StyleAlignment andMixup) for NR-IQA, which transfers sufficient knowledge from label-rich source domain data to label-free target domain images. Specifically, we find a more compact and reliable space i.e., feature style space for perception-oriented UDA based on an interesting observation, that the feature style (i.e., the mean and variance) of the deep layer in DNNs is exactly associated with the quality score in NR-IQA. Therefore, we propose to align the source and target domains in a more perceptual-oriented space i.e., the feature style space, to reduce the intervention from other quality-irrelevant feature factors. Furthermore, to increase the consistency (i.e., ordinal/continuous characteristics) between quality score and its feature style, we also propose a novel feature augmentation strategy Style Mixup, which mixes the feature styles (i.e., the mean and variance) before the last layer of DNNs together with mixing their labels. Extensive experimental results on many cross-domain settings (e.g., synthetic to authentic, and multiple distortions to one distortion) have demonstrated the effectiveness of our proposed StyleAM on NR-IQA.

The dense deployment of wireless nodes in the next generation of wireless local area networks (WLANs) poses a potential threat to network performance. Enhancing spatial reuse (SR) in WLANs can effectively address this issue. Dynamic clear channel assessment (CCA) threshold and transmit power control are crucial techniques to improve SR. This paper formulates the SR problem as a multi-armed bandit problem. A Bayesian optimization online learning algorithm with Gaussian process is proposed to optimize CCA thresholds and transmit power jointly. Finally, the proposed algorithm is compared with the default configuration and Thompson sampling algorithm across four performance metrics with the NS-3 simulator. The results demonstrate that our algorithm can significantly diminish cumulative regret, amplify total throughput, reduce the number of nodes in starvation, and improve overall network fairness.

The image distortions are complex and dynamically changing in the real-world scenario, due to the fast development of the image processing system. The blind image quality assessment (BIQA) models may encounter the challenge of processing images with distortion types never seen before deployment. However, existing BIQA models generally cannot evolve with unseen distortion types adaptively, which greatly limits the deployment and application of BIQA models in real-world scenarios. To address this problem, we propose a novel Lifelong blind Image Quality Assessment (LIQA) approach, targeting to achieve the lifelong learning of BIQA. Without accessing to previous training data, our proposed LIQA can not only learn new knowledge, but also mitigate the catastrophic forgetting of learned knowledge. Specifically, we adopt the Split-and-Merge distillation strategy to train a single-head network that makes task-agnostic predictions. In the split stage, we first employ a distortion-specific generator to generate pseudo features of each previously seen distortion. Then, we utilize an auxiliary multi-head regression network to keep the response of each distortion. In the merge stage, we replay the pseudo features and use the pseudo labels generated by the auxiliary multi-head network to distill the knowledge of the multiple heads, which can build the final regression single head. Extensive experiments demonstrate that LIQA can perform well in handling both inner-dataset distortion shift and cross-dataset distortion shift. More importantly, our model can achieve stable performance even if the task sequences are long.