Despite the impressive performance of large multimodal models (LMMs) in high-level visual tasks, their capacity for image quality assessment (IQA) remains limited. One main reason is that LMMs are primarily trained for high-level tasks (e.g., image captioning), emphasizing unified image semantics extraction under varied quality. Such semantic-aware yet quality-insensitive perception bias inevitably leads to a heavy reliance on image semantics when those LMMs are forced for quality rating. In this paper, instead of retraining or tuning an LMM costly, we propose a training-free debiasing framework, in which the image quality prediction is rectified by mitigating the bias caused by image semantics. Specifically, we first explore several semantic-preserving distortions that can significantly degrade image quality while maintaining identifiable semantics. By applying these specific distortions to the query/test images, we ensure that the degraded images are recognized as poor quality while their semantics remain. During quality inference, both a query image and its corresponding degraded version are fed to the LMM along with a prompt indicating that the query image quality should be inferred under the condition that the degraded one is deemed poor quality. This prior condition effectively aligns the LMM’s quality perception, as all degraded images are consistently rated as poor quality, regardless of their semantic difference. Finally, the quality scores of the query image inferred under different prior conditions (degraded versions) are aggregated using a conditional probability model. Extensive experiments on various IQA datasets show that our debiasing framework could consistently enhance the LMM performance and the code will be publicly available.

Recent efforts have repurposed the Contrastive Language-Image Pre-training (CLIP) model for No-Reference Image Quality Assessment (NR-IQA) by measuring the cosine similarity between the image embedding and textual prompts such as "a good photo" or "a bad photo." However, this semantic similarity overlooks a critical yet underexplored cue: the magnitude of the CLIP image features, which we empirically find to exhibit a strong correlation with perceptual quality. In this work, we introduce a novel adaptive fusion framework that complements cosine similarity with a magnitude-aware quality cue. Specifically, we first extract the absolute CLIP image features and apply a Box-Cox transformation to statistically normalize the feature distribution and mitigate semantic sensitivity. The resulting scalar summary serves as a semantically-normalized auxiliary cue that complements cosine-based prompt matching. To integrate both cues effectively, we further design a confidence-guided fusion scheme that adaptively weighs each term according to its relative strength. Extensive experiments on multiple benchmark IQA datasets demonstrate that our method consistently outperforms standard CLIP-based IQA and state-of-the-art baselines, without any task-specific training.

Coresets are compact, representative subsets of large datasets. While coreset selection methods have been extensively investigated in image classification, their direct application to image quality assessment (IQA) is hindered by the incoherent and structurally distinct nature of content and quality representations in IQA tasks. To address this gap, we propose Q-Diverse coreset, a framework tailored for IQA. Our method begins by extracting dual-view embeddings that are both content-aware and quality-aware, capturing semantic and perceptual nuances. Rather than directly combining these heterogeneous features, we construct separate pairwise distance matrices and fuse them in the distance space. This fusion transforms into a graph-based structure from which spectral embeddings are derived. Finally, a geometric diversity-based sampling strategy is applied in the spectral space to select a coreset that maximizes representativeness. Notably, Q-Diverse operates in a label-free manner, making it especially valuable in IQA, where collecting quality score annotations is computationally expensive and time-consuming. Experimental results on seven IQA benchmarks demonstrate that Q-Diverse enables the effective training of deep learning-based IQA architectures, even with limited data, impressively retaining performance. It achieves SRCC and PLCC values within 0.045 and 0.042 of those obtained from full-data training, using only 10% of the dataset on average. Our results establish Q-Diverse as a coreset selection method that enables efficient dataset curation as well as training and fine-tuning deep learning–based IQA models. Code is available at: https://github.com/Arpita2012/Q-Diverse.

Assessing the quality of artificial intelligence-generated images (AIGIs) plays a crucial role in their application in real-world scenarios. However, traditional image quality assessment (IQA) algorithms primarily focus on low-level visual perception, while existing IQA works on AIGIs overemphasize the generated content itself, neglecting its effectiveness in real-world applications. To bridge this gap, we propose AIGI-VC, a quality assessment database for AI-Generated Images in Visual Communication, which studies the communicability of AIGIs in the advertising field from the perspectives of information clarity and emotional interaction. The dataset consists of 2,500 images spanning 14 advertisement topics and 8 emotion types. It provides coarse-grained human preference annotations and fine-grained preference descriptions, benchmarking the abilities of IQA methods in preference prediction, interpretation, and reasoning. We conduct an empirical study of existing representative IQA methods and large multi-modal models on the AIGI-VC dataset, uncovering their strengths and weaknesses.

In this paper, we propose to compress human body video with interactive semantics, which can facilitate video coding to be interactive and controllable by manipulating semantic-level representations embedded in the coded bitstream. In particular, the proposed encoder employs a 3D human model to disentangle nonlinear dynamics and complex motion of human body signal into a series of configurable embeddings, which are controllably edited, compactly compressed, and efficiently transmitted. Moreover, the proposed decoder can evolve the mesh-based motion fields from these decoded semantics to realize the high-quality human body video reconstruction. Experimental results illustrate that the proposed framework can achieve promising compression performance for human body videos at ultra-low bitrate ranges compared with the state-of-the-art video coding standard Versatile Video Coding (VVC) and the latest generative compression schemes. Furthermore, the proposed framework enables interactive human body video coding without any additional pre-/post-manipulation processes, which is expected to shed light on metaverse-related digital human communication in the future.

Coreset selection improves training efficiency in deep learning but faces unique challenges in image quality assessment (IQA), where perceptual alignment with human vision and the interplay of distortions, semantics, and quality annotations are critical. Existing methods, designed for classification via static scoring criteria, fail to address IQA-specific multi-dimensional complexities, leading to suboptimal coreset construction. We propose perceptually guided coreset selection (PGCS), which employs adaptive sampling over a partitioned IQA latent space to dynamically balance distortion characteristics, perceptual quality, and semantic content. Latent space partitions are created based on the coverage of data points, ensuring that each partition reflects the overall structure of the dataset. Our adaptive sampling strategy dynamically adjusts the selection range, ensuring that local densities are preserved and better represented. Evaluated across five IQA benchmarks, PGCS-optimized coresets (5% − 90% of original data) reduce dataset redundancy and annotation noise while achieving ≤ 0.09 PLCC and ≤ 0.09 SRCC degradation on average with 5% data, matching or surpassing full-data training. Our work advances data-efficient learning by prioritizing perceptual alignment, offering a framework adaptable to human-centric vision tasks. Code is available at: https://github.com/Arpita2012/PGCS.

In this work, we propose a novel framework to enable diffusion models to adapt their generation quality based on real-time network bandwidth constraints. Traditional diffusion models produce high-fidelity images by performing a fixed number of denoising steps, regardless of downstream transmission limitations. However, in practical cloud-to-device scenarios, limited bandwidth often necessitates heavy compression, leading to loss of fine textures and wasted computation. To address this, we introduce a joint end-to-end training strategy where the diffusion model is conditioned on a target quality level derived from the available bandwidth. During training, the model learns to adaptively modulate the denoising process, enabling early-stop sampling that maintains perceptual quality appropriate to the target transmission condition. Our method requires minimal architectural changes and leverages a lightweight quality embedding to guide the denoising trajectory. Experimental results demonstrate that our approach significantly improves the visual fidelity of bandwidth-adapted generations compared to naive early-stopping, offering a promising solution for efficient image delivery in bandwidth-constrained environments. Code is available at: https://github.com/xzhang9308/BADiff.

Despite substantial efforts dedicated to the design of heuristic models for omnidirectional (i.e., 360°) image quality assessment (OIQA), a conspicuous gap remains due to the lack of consideration for the diversity of viewing behaviors that leads to the varying perceptual quality of 360° images. Two critical aspects underline this oversight: the neglect of viewing conditions that significantly sway user gaze patterns and the overreliance on a single viewport sequence from the 360° image for quality inference. To address these issues, we introduce a unique generative scanpath representation (GSR) for effective quality inference of 360° images, which aggregates varied perceptual experiences of multi-hypothesis users under a predefined viewing condition. More specifically, given a viewing condition characterized by the starting point of viewing and exploration time, a set of scanpaths consisting of dynamic visual fixations can be produced using an apt scanpath generator. Following this vein, we use the scanpaths to convert the 360° image into the unique GSR, which provides a global overview of gazed-focused contents derived from scanpaths. As such, the quality inference of the 360° image is swiftly transformed to that of GSR. We then propose an efficient OIQA computational framework by learning the quality maps of GSR. Comprehensive experimental results validate that the predictions of the proposed framework are highly consistent with human perception in the spatiotemporal domain, especially in the challenging context of locally distorted 360° images under varied viewing conditions. The code will be released at https://github.com/xiangjieSui/GSR.

Deep neural networks pre-trained on ImageNet have demonstrated remarkable transferability for developing effective full-reference image quality assessment (FR-IQA) models. However, existing approaches typically demand pixel-level alignment between reference and distorted images-a requirement that poses significant challenges in practical scenarios involving natural photography and texture similarity evaluation. To address this limitation, we propose a novel FR-IQA model leveraging deep statistical similarity derived from pre-trained features without relying on spatial co-location of these features or requiring fine-tuning with mean opinion scores. Specifically, we employ distance correlation, a potent yet relatively underexplored statistical measure, to quantify similarity between reference and distorted images within a deep feature space. The distance correlation is computed via the ratio of the distance covariance to the product of their respective distance standard deviations, for which we derive a closed-form solution using the inner product of deep double-centered distance matrices. Extensive experimental evaluations across diverse IQA benchmarks demonstrate the superiority and robustness of the proposed model. Furthermore, we demonstrate the utility of our model for optimizing texture synthesis and neural style transfer tasks, achieving state-of-the-art performance in both quantitative measures and qualitative assessments. The implementation is publicly available at https://github.com/h4nwei/DeepDC.

An ideal full-reference image quality (FR-IQA) model should exhibit both high separability for images with different quality and compactness for images with the same or indistinguishable quality. However, existing learning-based FR-IQA models that directly compare images in deep-feature space, usually overly emphasize the quality separability, neglecting to maintain the compactness when images are of similar quality. In our work, we identify that the perception bias mainly stems from an inappropriate subspace where images are projected and compared. For this issue, we propose a Debiased Mapping based quality Measure (DMM), leveraging orthonormal bases formed by singular value decomposition (SVD) in the deep features domain. The SVD effectively decomposes the quality variations into singular values and mapping bases, enabling quality inference with more reliable feature difference measures. Extensive experimental results reveal that our proposed measure could mitigate the perception bias effectively and demonstrates excellent quality prediction performance on various IQA datasets.

While recent advancements in large multimodal models (LMMs) have significantly improved their abilities in image quality assessment (IQA) relying on absolute quality rating, how to transfer reliable relative quality comparison outputs to continuous perceptual quality scores remains largely unexplored. To address this gap, we introduce an all-around LMM-based NR-IQA model, which is capable of producing qualitatively comparative responses and effectively translating these discrete comparison outcomes into a continuous quality score. Specifically, during training, we present to generate scaled-up comparative instructions by comparing images from the same IQA dataset, allowing for more flexible integration of diverse IQA datasets. Utilizing the established large-scale training corpus, we develop a human-like visual quality comparator. During inference, moving beyond binary choices, we propose a soft comparison method that calculates the likelihood of the test image being preferred over multiple predefined anchor images. The quality score is further optimized by maximum a posteriori estimation with the resulting probability matrix. Extensive experiments on nine IQA datasets validate that the Compare2Score effectively bridges text-defined comparative levels during training with converted single image quality scores for inference, surpassing state-of-the-art IQA models across diverse scenarios. Moreover, we verify that the probability-matrix-based inference conversion not only improves the rating accuracy of Compare2Score but also zero-shot general-purpose LMMs, suggesting its intrinsic effectiveness.

Abstract Temporal inconsistency is the annoying artifact that has been commonly introduced in low-light video enhancement, but current methods tend to overlook the significance of utilizing both data-centric clues and model-centric design to tackle this problem. In this context, our work makes a comprehensive exploration from the following three aspects. First, to enrich the scene diversity and motion flexibility, we construct a synthetic diverse low/normal-light paired video dataset with a carefully designed low-light simulation strategy, which can effectively complement existing real captured datasets. Second, for better temporal dependency utilization, we develop a Temporally Consistent Enhancer Network (TCE-Net) that consists of stacked 3D convolutions and 2D convolutions to exploit spatial-temporal clues in videos. Last, the temporal dynamic feature dependencies are exploited to obtain consistency constraints for different frame indexes. All these efforts are powered by a Spatial-Temporal Compatible Learning (STCL) optimization technique, which dynamically constructs specific training loss functions adaptively on different datasets. As such, multiple-frame information can be effectively utilized and different levels of information from the network can be feasibly integrated, thus expanding the synergies on different kinds of data and offering visually better results in terms of illumination distribution, color consistency, texture details, and temporal coherence. Extensive experimental results on various real-world low-light video datasets clearly demonstrate the proposed method achieves superior performance to state-of-the-art methods. Our code and synthesized low-light video database will be publicly available at https://github.com/lingyzhu0101/low-light-video-enhancement.git .

Spatio-temporal resolution adaptive (STRA) coding has been repeatedly proven to be a promising way to improve coding efficiency and reduce coding complexity. The wide consensus is that the optimal subsampled resolution and frame rate should be governed by so- called generalized rate-distortion performance based on the ultimately perceived distortion. However, it is non-trivial to accurately predict the quality of reconstructed videos due to the fact that the distortion originates from both subsampling and compression. To address this issue, we propose a novel video quality assessment model that is fully aware of the information available in downsampled videos for compression, such as resolution and frame rate. More specifically, the proposed model relies on quality-aware spatial features that are extracted by an image quality fine-tuned backbone. Subsequently, the spatio-temporal quality is modeled based on the transformer encoder, which is adaptive to the downsampling spatial and temporal resolutions. This enables the transformer encoder to produce discriminative features that capture long-range temporal dependencies related to the current context. The quality score, which is the output of the transformer encoder, thus reflects both the influence of the subsampling and compression. We conduct extensive experiments that demonstrate the superiority of the proposed model over state-of-the-art methods on four subsampling and compression video quality datasets. Furthermore, we apply the proposed model to bitrate ladder optimization, leading to a perceptual-aware spatial and temporal downsampling strategy that yields promising bitrate savings. The source codes of the proposed model will be publicly available athttps://github.com/h4nwei/STRA-VQA.

While abundant research has been conducted on improving high-level visual understanding and reasoning capabilities of large multimodal models (LMMs), their image quality assessment (IQA) ability has been relatively under-explored. Here we take initial steps towards this goal by employing the two-alternative forced choice (2AFC) prompting, as 2AFC is widely regarded as the most reliable way of collecting human opinions of visual quality. Subsequently, the global quality score of each image estimated by a particular LMM can be efficiently aggregated using the maximum a posteriori estimation. Meanwhile, we introduce three evaluation criteria: consistency, accuracy, and correlation, to provide comprehensive quantifications and deeper insights into the IQA capability of five LMMs. Extensive experiments show that existing LMMs exhibit remarkable IQA ability on coarse-grained quality comparison, but there is room for improvement on fine-grained quality discrimination. The proposed dataset sheds light on the future development of IQA models based on LMMs. The codes will be made publicly available athttps://github.com/h4nwei/2AFC-LMMs.

The statistical regularities of natural images, referred to as natural scene statistics, play an important role in no-reference image quality assessment. However, it has been widely acknowledged that screen content images (SCIs), which are typically computer generated, do not hold such statistics. Here we make the first attempt to learn the statistics of SCIs, based upon which the quality of SCIs can be effectively determined. The underlying mechanism of the proposed approach is based upon the mild assumption that the SCIs, which are not physically acquired, still obey certain statistics that could be understood in a learning fashion. We empirically show that the statistics deviation could be effectively leveraged in quality assessment, and the proposed method is superior when evaluated in different settings. Extensive experimental results demonstrate the Deep Feature Statistics based SCI Quality Assessment (DFSS-IQA) model delivers promising performance compared with existing NR-IQA models and shows a high generalization capability in the cross-dataset settings. The implementation of our method is publicly available at https://github.com/Baoliang93/DFSS-IQA.

There is a growing consensus in the research community that the optimization of low-light image enhancement approaches should be guided by the visual quality perceived by end users. Despite the substantial efforts invested in the design of low-light enhancement algorithms, there has been comparatively limited focus on assessing subjective and objective quality systematically. To mitigate this gap and provide a clear path towards optimizing low-light image enhancement for better visual quality, we propose a gap-closing framework. In particular, our gap-closing framework starts with the creation of a large-scale dataset for Subjective QUality Assessment of REconstructed LOw-Light Images (SQUARE-LOL). This database serves as the foundation for studying the quality of enhanced images and conducting a comprehensive subjective user study. Subsequently, we propose an objective quality assessment measure that plays a critical role in bridging the gap between visual quality and enhancement. Finally, we demonstrate that our proposed objective quality measure can be incorporated into the process of optimizing the learning of the enhancement model toward perceptual optimality. We validate the effectiveness of our proposed framework through both the accuracy of quality prediction and the perceptual quality of image enhancement.

Opinion-Unaware Blind Image Quality Assessment (OU-BIQA) models aim to predict image quality without training on reference images and subjective quality scores. Thereinto, image statistical comparison is a classic paradigm, while the performance is limited by the representation ability of visual descriptors. Deep features as visual descriptors have advanced IQA in recent research, but they are discovered to be highly texture-biased and lack shape-bias. On this basis, we find out that image shape and texture cues respond differently toward distortions, and the absence of either one results in an incomplete image representation. Therefore, to formulate a well-rounded statistical description for images, we utilize the shape-biased and texture-biased deep features produced by Deep Neural Networks (DNNs) simultaneously. More specifically, we design a Shape-Texture Adaptive Fusion (STAF) module to merge shape and texture information, based on which we formulate quality-relevant image statistics. The perceptual quality is quantified by the variant Mahalanobis distance between the inner and outer Deep Shape-Texture Statistics (DSTS), wherein the inner and outer statistics respectively describe the quality fingerprints of the distorted image and natural images. The proposed DSTS delicately utilizes shape-texture statistical relations between different data scales in the deep domain and achieves state-of-the-art (SOTA) quality prediction performance on images with artificial and authentic distortions.

Scanpath prediction for 360° images aims to produce dynamic gaze behaviors based on the human visual perception mechanism. Most existing scanpath prediction methods for 360° images do not give a complete treatment of the time-dependency when predicting human scanpath, resulting in inferior performance and poor generalizability. In this paper, we present a scanpath prediction method for 360° images by designing a novel Deep Markov Model (DMM) architecture, namely ScanDMM. We propose a semantics-guided transition function to learn the nonlinear dynamics of time-dependent attentional landscape. Moreover, a state initialization strategy is proposed by considering the starting point of viewing, enabling the model to learn the dynamics with the correct “launcher”. We further demonstrate that our model achieves state-of-the-art performance on four 360° image databases, and exhibit its generalizability by presenting two applications of applying scanpath prediction models to other visual tasks - saliency detection and image quality assessment, expecting to provide profound insights into these fields.

Decentralizing crowdsourcing using blockchain removes the trusted mediator who may cause social biases in data aggregation and uncertainties in ensuring proper rewards to workers. Permissionless blockchain discloses all data on public ledgers, which compromises the privacy and anonymity of workers and induces free-riders. State-of-the-art anonymous crowdsourcing systems enable anonymity through identity registration of workers and a trusted setup for key generation. However, these systems fail to support anonymous payments to workers, which may compromise the identities of workers. In this paper, we incorporate anonymous payments in crowdsourcing and dispense with identity registration and trusted setup to support open anonymous participation from any worker. Our solution is based on the decentralized anonymous payment systems (e.g., Zerocoin), commitment schemes, and efficient non-interactive zero-knowledge proofs.

Distortions from spatial and temporal domains have been identified as the dominant factors that govern the visual quality. Though both have been studied independently in deep learning-based user-generated content (UGC) video quality assessment (VQA) by frame-wise distortion estimation and temporal quality aggregation, much less work has been dedicated to the integration of them with deep representations. In this paper, we propose a SpatioTemporal Interactive VQA (STI-VQA) model based upon the philosophy that video distortion can be inferred from the integration of both spatial characteristics and temporal motion, along with the flow of time. In particular, for each timestamp, both the spatial distortion explored by the feature statistics and local motion captured by feature difference are extracted and fed to a transformer network for the motion aware interaction learning. Meanwhile, the information flow of spatial distortion from the shallow layer to the deep layer is constructed adaptively during the temporal aggregation. The transformer network enjoys an advanced advantage for long-range dependencies modeling, leading to superior performance on UGC videos. Experimental results on five UGC video benchmarks demonstrate the effectiveness and efficiency of our STI-VQA model, and the source code will be available online athttps://github.com/h4nwei/STI-VQA.

Existing deep learning-based full-reference IQA (FR-IQA) models usually predict the image quality in a deterministic way by explicitly comparing the features, gauging how severely distorted an image is by how far the corresponding feature lies from the space of the reference images. Herein, we look at this problem from a different viewpoint and propose to model the quality degradation in perceptual space from a statistical distribution perspective. As such, the quality is measured based upon the Wasserstein distance in the deep feature domain. More specifically, the 1D Wasserstein distance at each stage of the pre-trained VGG network is measured, based on which the final quality score is performed. The deep Wasserstein distance (DeepWSD) performed on features from neural networks enjoys better interpretability of the quality contamination caused by various types of distortions and presents an advanced quality prediction capability. Extensive experiments and theoretical analysis show the superiority of the proposed DeepWSD in terms of both quality prediction and optimization. The implementation of our method is publicly available at https://github.com/Buka-Xing/DeepWSD.

Data sensing and gathering is an essential task for various information-driven services in smart cities. On the one hand, Internet of Things (IoT) sensors can be deployed at certain fixed locations to capture data reliably but suffer from limited sensing coverage. On the other hand, data can also be gathered dynamically through crowdsensing contributed by voluntary users but suffer from its unreliability and the lack of incentives for users’ contributions. In this article, we explore an integrated paradigm called “ hybrid sensing ” that harnesses both IoT-sensing and crowdsensing in a complementary manner. In hybrid sensing, users are incentivized to provide sensing data not covered by IoT sensors and provide crowdsourced feedback to assist in calibrating IoT-sensing. Their contributions will be rewarded with credits that can be redeemed to retrieve synthesized information from the hybrid system. In this article, we develop a hybrid sensing system that supports explicit user privacy—IoT sensors are obscured physically to prevent capturing private user data, and users interact with a crowdsensing server via a privacy-preserving protocol to preserve their anonymity. A key application of our system is smart parking, by which users can inquire and find the available parking spaces in outdoor parking lots. We implemented our hybrid sensing system for smart parking and conducted extensive empirical evaluations. Finally, our hybrid sensing system can be potentially applied to other information-driven services in smart cities.

In this paper, we propose a no-reference (NR) image quality assessment (IQA) method via feature level pseudo-reference (PR) hallucination. The proposed quality assessment framework is rooted in the view that the perceptually meaningful features could be well exploited to characterize the visual quality, and the natural image statistical behaviors are exploited in an effort to deliver the accurate predictions. Herein, the PR features from the distorted images are learned by a mutual learning scheme with the pristine reference as the supervision, and the discriminative characteristics of PR features are further ensured with the triplet constraints. Given a distorted image for quality inference, the feature level disentanglement is performed with an invertible neural layer for final quality prediction, leading to the PR and the corresponding distortion features for comparison. The effectiveness of our proposed method is demonstrated on four popular IQA databases, and superior performance on cross-database evaluation also reveals the high generalization capability of our method. The implementation of our method is publicly available on https://github.com/Baoliang93/FPR.

Multi-exposure image fusion (MEF) algorithms have been used to merge a stack of low dynamic range images with various exposure levels into a well-perceived image. However, little work has been dedicated to predicting the visual quality of fused images. In this work, we propose a novel and efficient objective image quality assessment (IQA) model for MEF images of both static and dynamic scenes based on superpixels and an information theory adaptive pooling strategy. First, with the help of superpixels, we divide fused images into large- and small-changed regions using the structural inconsistency map between each exposure and fused images. Then, we compute the quality maps based on the Laplacian pyramid for large- and small-changed regions separately. Finally, an information theory induced adaptive pooling strategy is proposed to compute the perceptual quality of the fused image. Experimental results on three public databases of MEF images demonstrate the proposed model achieves promising performance and yields a relatively low computational complexity. Additionally, we also demonstrate the potential application for parameter tuning of MEF algorithms.

As smartphones become people's primary cameras to take photos, the quality of their cameras and the associated computational photography modules has become a de facto standard in evaluating and ranking smartphones in the consumer market. We conduct so far the most comprehensive study of perceptual quality assessment of smartphone photography. We introduce the Smartphone Photography Attribute and Quality (SPAQ) database, consisting of 11,125 pictures taken by 66 smartphones, where each image is attached with so far the richest annotations. Specifically, we collect a series of human opinions for each image, including image quality, image attributes (brightness, colorfulness, contrast, noisiness, and sharpness), and scene category labels (animal, cityscape, human, indoor scene, landscape, night scene, plant, still life, and others) in a well-controlled laboratory environment. The exchangeable image file format (EXIF) data for all images are also recorded to aid deeper analysis. We also make the first attempts using the database to train blind image quality assessment (BIQA) models constructed by baseline and multi-task deep neural networks. The results provide useful insights on how EXIF data, image attributes and high-level semantics interact with image quality, how next-generation BIQA models can be designed, and how better computational photography systems can be optimized on mobile devices. The database along with the proposed BIQA models are available at https://github.com/h4nwei/SPAQ.

A common approach to high dynamic range (HDR) imaging is to capture multiple images of different exposures followed by multi-exposure image fusion (MEF) in either radiance or intensity domain. A predominant problem of this approach is the introduction of the ghosting artifacts in dynamic scenes with camera and object motion. While many MEF methods (often referred to as deghosting algorithms) have been proposed for reduced ghosting artifacts and improved visual quality, little work has been dedicated to perceptual evaluation of their deghosting results. Here we first construct a database that contains 20 multiexposure sequences of dynamic scenes and their corresponding fused images by nine MEF algorithms. We then carry out a subjective experiment to evaluate fused image quality, and find that none of existing objective quality models for MEF provides accurate quality predictions. Motivated by this, we develop an objective quality model for MEF of dynamic scenes. Specifically, we divide the test image into static and dynamic regions, measure structural similarity between the image and the corresponding sequence in the two regions separately, and combine quality measurements of the two regions into an overall quality score. Experimental results show that the proposed method significantly outperforms the state-of-the-art. In addition, we demonstrate the promise of the proposed model in parameter tuning of MEF methods.1.

We propose a fast multi-exposure image fusion (MEF) method, namely MEF-Net, for static image sequences of arbitrary spatial resolution and exposure number. We first feed a low-resolution version of the input sequence to a fully convolutional network for weight map prediction. We then jointly upsample the weight maps using a guided filter. The final image is computed by a weighted fusion. Unlike conventional MEF methods, MEF-Net is trained end-to-end by optimizing the perceptually calibrated MEF structural similarity (MEF-SSIM) index over a database of training sequences at full resolution. Across an independent set of test sequences, we find that the optimized MEF-Net achieves consistent improvement in visual quality for most sequences, and runs 10 to 1000 times faster than state-of-the-art methods. The code is made publicly available at.

In complex social-ecological systems, multiple agents with diverse objectives take actions that affect the long-term dynamics of the system. Common pool resources are a subset of such systems, where property rights are typically poorly defined and dynamics are unknown a priori, creating a social dilemma reflected by the well-known `tragedy of the commons.' In this paper, we investigated the efficacy of deep reinforcement learning in a multi-agent setting of a common pool resource system. We used an abstract mathematical model of the system, represented as a partially-observable general-sum Markov game. In the first set of experiments, the independent agents used a deep Q-Network with discrete action spaces to guide decision-making. However, significant shortcomings were evident. Consequently, in a second set of experiments, a Deep Deterministic Policy Gradient learning model with continuous state and action spaces guided agent learning. Simulation results show that agents performed significantly better in terms of both sustainability and economic goals when using the second deep learning model. Despite the fact that agents do not have perfect foresight nor understanding of the implications of their `harvesting' efforts, deep reinforcement learning can be used effectively to `learn in the commons'.

Over the past decade, many multi-exposure image fusion (MEF) methods have been proposed to obtain perceptually appealing results for both static and dynamic scenes. However, little work has been dedicated to evaluate perceptual quality of fused images. In this work, we propose a novel objective image quality assessment (IQA) model for MEF images of both static and dynamic scenes based on a pyramid subband contrast preservation scheme and an information theory adaptive pooling strategy. Firstly, we decompose the images using a Laplacian pyramid, and each pyramid subband is used to extract gradient and contrast features. Secondly, we binarize the structure inconsistency map between each exposure and fused image to obtain large-changed and small-changed regions. Finally, an information theory adaptive pooling strategy is used to combine these two quality scores from the individual regions. Experimental results on two large scale MEF databases of static and dynamic sequences show that the proposed model can obtain superior performance than state-of-the-art models designed for fused images.

High dynamic range (HDR) imaging techniques aim to extend the dynamic range of images that cannot be well captured using conventional camera sensors. A common practice is to take a stack of pictures with different exposure levels and fuse them to produce a final image with more details. However, a small displacement between images caused by either camera or scene motion would void the benefits and cause the so-called ghosting artifacts. Over the past decade, many HDR deghosting algorithms have been proposed, but little work has been dedicated to evaluate HDR deghosting results either subjectively or objectively. In this work, we present a comprehensive subjective study for HDR deghosting. Specifically, we create a database that contains 20 dynamic image sequences and their corresponding deghosting results by 9 deghosting algorithms. A subjective user study is then carried out to evaluate the perceptual quality of deghosted images. The experimental results demonstrate the performance and limitations of existing HDR deghosting algorithm as well as no-reference image quality assessment models. In the future, we will make the database available to the public.