Image degradation synthesis is highly desirable in a wide variety of applications ranging from image restoration to simulating artistic effects. Existing models are designed to generate one specific or a narrow set of degradations, which often require user-provided degradation parameters. As a result, they lack the generalizability to synthesize degradations beyond their initial design or adapt to other applications. Here we propose the first universal degradation model that can synthesize a broad spectrum of complex and realistic degradations containing both homogeneous (global) and inhomogeneous (spatially varying) components. Our model automatically extracts and disentangles homogeneous and inhomogeneous degradation features, which are later used for degradation synthesis without user intervention. A disentangle-by-compression method is proposed to separate degradation information from images. Two novel modules for extracting and incorporating inhomogeneous degradations are created to model inhomogeneous components in complex degradations. We demonstrate the model's accuracy and adaptability in film-grain simulation and blind image restoration tasks. The demo video, code, and dataset of this project will be released at github.com/yangwenbo99/content-degradation-disentanglement.

Over the past decades, numerous Image Quality Assessment (IQA) models have emerged, aiming to predict the perceptual quality of images. However, individual models are often biased toward certain types of image content or distortions, depending on the design principle and process. An intuitive idea is to harness the strengths and mitigate the weaknesses of each IQA model, by fusing the scores of multiple models into a stronger one. Here we make one of the first attempts to seek an optimal solution for the idea and propose a general framework for unsupervised IQA score fusion using deep Maximum a Posteriori (MAP) estimation. The proposed model conducts fine-grained uncertainty estimation at the score level to increase the accuracy and reduce the uncertainty in fused predictions. Comprehensive experiments demonstrate the superiority of the proposed model over individual IQA models and other fusion methods. It also exhibits an interesting capability of rejecting "bad" models in the fusion process.

Mobile edge computing (MEC) brings abundant computing resources to the edge networks, which supports users in offloading their tasks to the edge instead of the cloud, thereby reducing service delay and improving users' quality of experience. In this paper, we consider a three-tier multi-user multi-task offloading model, which contains multiple users with each user possessing multiple tasks, multiple base stations (BSs) with edge servers and a remote cloud. Taking into account the selfishness of individuals in the MEC system, we respectively formulate optimization problems for users, BSs and the cloud. Users aim to make their offloading strategies to minimize their respective costs, while BSs and the cloud aim to make their computation resource allocation decisions to minimize their respective task completion delays. We model the interaction among these selfish individuals based on Stackelberg game, where users act as leaders and BSs and the cloud act as followers. By using backward induction, we prove the existence of Stackelberg Equilibrium (SE). We further propose a distributed algorithm that enables the system to reach the SE, which includes three user selection strategies for the BSs. The numerical results demonstrate the superiority of the proposed scheme compared with several approaches.

Banding or false contour is an annoying visual artifact whose impact negatively degrades the perceptual quality of visual content. Since users are increasingly expecting better visual quality from such content and banding leads to deteriorated quality-of-experience, the area of banding removal or debanding has taken paramount importance. Existing debanding approaches are mostly knowledge-driven, while data-driven debanding approaches remain surprisingly missing. In this work, we construct a large-scale dataset of 51,490 pairs of corresponding pristine and banded image patches, which enables us to make one of the first attempts at developing a deep learning based banding artifact removal method for images that we name deep debanding network (deepDeband). We also develop a bilateral weighting scheme that fuses patch-level debanding results to full-size images. Extensive performance evaluation shows that deepDeband is successful at greatly reducing banding artifacts in images, outperforming existing methods both quantitatively and visually. The proposed algorithm and dataset are made publicly available.1

Thermal cameras can capture images invariant to illumination conditions. However, thermal facial images are difficult to be recognized by human examiners. In this letter, an end-to-end framework, which consists of a generative network and a detector network, is proposed to translate thermal facial images into visible ones. The generative network aims at generating visible images given the thermal ones. The detector can locate important facial landmarks on visible faces and help the generative network to generate more realistic images that are easier to be recognized. As demonstrated in the experiments, the faces generated by our method have good visual quality and maintain identity preserving features.