In recent years, learning-based underwater image enhancement (UIE) techniques have rapidly evolved. However, distribution shifts between high-quality enhanced outputs and natural images can hinder semantic cue extraction for downstream vision tasks, thereby limiting the adaptability of existing enhancement models. To address this challenge, this work proposes a new learning mechanism that leverages Vision-Language Models (VLMs) to empower UIE models with semantic-sensitive capabilities. To be concrete, our strategy first generates textual descriptions of key objects from a degraded image via a VLM. Subsequently, a text-image alignment model remaps these relevant descriptions back onto the image to produce a spatial semantic guidance map. This map then steers the UIE network through a dual-guidance mechanism, which combines cross-attention and an explicit alignment loss. This forces the network to focus its restorative power on semantic-sensitive regions during image reconstruction, rather than pursuing a globally uniform improvement, thereby ensuring the faithful restoration of key object features. Experiments confirm that when our strategy is applied to different UIE baselines, significantly boosts their performance on perceptual quality metrics as well as enhances their performance on detection and segmentation tasks, validating its effectiveness and adaptability.

Underwater image quality assessment (UIQA) is hindered by complex degradation and domain shifts across aquatic environments. Existing no-reference IQA methods rely on costly and subjective mean opinion scores (MOS), which limit their generalization to unseen domains. To overcome these challenges, we propose SCUIA, an unsupervised UIQA framework leveraging semantic contrastive learning for quality prediction without human annotations. Specifically, we introduce a vision-language contrastive learning strategy that aligns image features with textual embeddings in a unified semantic space, capturing implicit degradation-quality correlations. We further enhance quality discrimination with a hierarchical contrastive learning mechanism that combines image-specific statistical priors and semantic prompts. A triplet-based inter-group contrastive loss explicitly models relative quality relationships. To tackle cross-domain variations, we develop an unsupervised domain adaptation module that uses local statistical features to guide CLIP fine-tuning to disentangle domain-invariant quality representations from domain-specific noise. This enables zero-shot cross-domain quality prediction without labeled data. Extensive experiments on public UIQA benchmarks demonstrate significant improvements over existing methods, highlighting superior generalization and domain adaptability.

• Propose a multimodal-inspired underwater video enhancement framework. • Introduce collision-aware noise injection to simulate feature-level conflicts. • Design a hybrid ViT-convolutional architecture with low computational cost. • Achieve improved clarity and temporal consistency across underwater frames. Underwater video enhancement addresses degradation from absorption, scattering, and turbidity, which hinders visual tasks such as detection and tracking. Unlike traditional single-frame methods, we treat temporal cues, occlusion patterns, and structured degradations as implicit modalities within video streams. To this end, we propose CAECNet (Collision-Attack Error Correction Network), a novel multimodal-inspired underwater video enhancement network that integrates the ‘Collision Attack’ training strategy with the ‘Error Correction’ mechanism. This network overcomes the limitations of traditional single-frame enhancement methods, implementing high-precision and real-time inference. It improves temporal perception through multi-frame fusion and utilizes previous frames to assist real-time inference, meeting the demands of dynamic processing. By incorporating a Vision Transformer (ViT) and a lightweight depthwise separable convolution module, the network enhances spatial feature representation and computational efficiency. A branching-based error correction upsampler is designed to correct feature representation errors and reduce information entropy loss, thereby improving video detail restoration quality. The “Collision Attack” training strategy injects structured noise to accelerate network feature learning and reduce computational costs. Experimental results show that CAECNet significantly outperforms existing methods on multiple underwater video datasets, improving image clarity, inter-frame consistency, and computational efficiency, making it suitable for underwater robotic intelligent perception tasks.

Color distortion and structural degradation in underwater images are classic challenges in underwater image enhancement. The core goal is to restore degraded images to high-quality images with both color and structure that conform to visual perception. However, in the traditional RGB space, these two issues are highly coupled, resulting in existing enhancement methods often neglecting one over the other. To address this challenge, we propose a guided diffusion model based on the principle of decoupling. Our key insight is that in perceptual color spaces such as HSV, color (H, S) and structure (V) are naturally separated. To exploit this property, we first design an adaptive perceptual guidance module, which analyzes the degraded HSV image and generates two orthogonal guidance signals: a color guide and a structure guide, which guide the denoising process of the diffusion model. To ensure that this decoupled guidance is faithfully implemented, we propose a corresponding decoupled loss optimization module, which uses independent loss functions to supervise the final output color and structure. By combining the forward decoupled guidance with the backward decoupled supervision, we construct a closed-loop optimization framework. This framework enables the model to collaboratively optimize color and structure under various degradation scenarios. Extensive experiments demonstrate that our proposed method outperforms existing state-of-the-art approaches in a variety of underwater scenes, particularly those degraded by color casts and haze. Furthermore, it exhibits superior performance on no-reference image quality assessment metrics. The source code is available at https://github.com/zy-world/DCD-UIE.

Recent advances in learning-based underwater image enhancement have achieved remarkable progress. However, the inherent diversity and complexity of underwater scenes still limit the ability of existing approaches to simultaneously restore fine structural details and global image layouts. To address this challenge, we propose a Resonant Fusion (ReFu) framework that explicitly leverages complementary information in both spatial and frequency domains. Specifically, we design a frequency decomposer and a spatial decomposer to capture high- and low-frequency cues from different perspectives. A resonant fuser is then introduced to adaptively integrate high-frequency resonances for detail refinement and low-frequency resonances for structural consistency. This fine-grained cross-domain fusion significantly improves structural preservation and detail enhancement, thereby generating visually more natural and perceptually friendly underwater images. Extensive quantitative and qualitative evaluations across diverse underwater benchmarks show that ReFu consistently surpasses state-of-the-art methods by a clear margin. Comprehensive ablation studies further validate the effectiveness of each module and prove the necessity of the proposed ReFu mechanism. Our code is available at https://github.com/CircleQa/ReFu-main.

Monocular depth estimation is critical for applications such as autonomous driving and scene reconstruction. While existing methods perform well under normal scenarios, their performance declines in adverse weather, due to challenging domain shifts and difficulties in extracting scene information. To address this issue, we present a robust monocular depth estimation method called ACDepth from the perspective of high-quality training data generation and domain adaptation. Specifically, we introduce a one-step diffusion model for generating samples that simulate adverse weather conditions, constructing a multi-tuple degradation dataset during training. To ensure the quality of the generated degradation samples, we employ LoRA adapters to fine-turn the generation weights of diffusion model. Additionally, we integrate circular consistency loss and adversarial training to guarantee the fidelity and naturalness of the scene contents. Furthermore, we elaborate on a multi-granularity knowledge distillation strategy (MKD) that encourages the student network to absorb knowledge from both the teacher model and pretrained Depth Anything V2. This strategy guides the student model in learning degradation-agnostic scene information from various degradation inputs. In particular, we introduce an ordinal guidance distillation mechanism (OGD) that encourages the network to focus on uncertain regions through differential ranking, leading to a more precise depth estimation. Experimental results demonstrate that our ACDepth surpasses md4all-DD by 2.50% for night scene and 2.61% for rainy scene on the nuScenes dataset in terms of the absRel metric.

Underwater video enhancement is crucial for marine research and monitoring applications, particularly in the context of the Internet of Things (IoT), where autonomous underwater vehicles (AUVs) and sensor networks are deployed for environmental monitoring and tracking marine life. However, the scarcity of undistorted underwater video data and distortions, such as motion blur and water turbidity, limit the effectiveness of enhancement models. Existing methods typically focus on frame-by-frame enhancement and overlook temporal coherence and computational efficiency. To address these issues, we propose SGUVE-Net (Semantic-Guided Underwater Video Enhancement Network), which combines a multi-scale feature-aware network with a semantic branch for localized enhancement. The main branch employs an encoder-decoder architecture, combining spatial group shifting and dual attention mechanisms to fully exploit contextual information for precise alignment. In contrast, the semantic branch focuses on enhancing key regions of the video frames by incorporating high-level semantic cues, which improves motion tracking accuracy and mitigates motion blur, thereby enhancing video quality for real-time IoT applications. They complement each other to achieve differentiated modeling of static background details and dynamic target features. Experimental results show that SGUVE-Net outperforms state-of-the-art methods across several metrics, providing an effective solution for underwater video enhancement in IoT systems.

Underwater robots rely on high-quality visual data for precise monitoring and manipulation, yet complex underwater environments often degrade image quality through color distortion, texture blurring, and detail loss. Existing enhancement methods partially address these issues, but fail to effectively decouple nonlinear relationships among degradation factors, leading to inconsistent performance. To address these challenges, we propose a degradation-content decoupling-based underwater image enhancement network (DCDN). The framework integrates a super-fusion cascade module for dynamic feature weighting, reducing artifacts, and combines multichannel color space transformation with texture-guided correction to decouple and optimize degradation factors. This approach improves color fidelity and texture detail restoration by refining color information and adapting local textures. Experiments on public datasets demonstrate that DCDN outperforms existing methods in various underwater scenarios. This work enhances the visual capabilities of underwater robots, supporting intelligent transportation applications, such as marine logistics and underwater inspections.

Feature drift is caused by the dynamic coupling of target features and degradation factors, which reduce underwater detector performance. We redefine feature drift as the instability of target features within boundary constraints while solving partial differential equations (PDEs). From this insight, we propose the Spatial Residual (SR) block, which uses SkipCut to establish effective constraints across the network width for solving PDEs and optimizes the solution space. It is implemented as a general-purpose backbone with 5 Spatial Residuals (BSR5) for complex feature scenarios. Specifically, BSR5 extracts discrete channel slices through SkipCut, where each sliced feature is parsed within the appropriate data capacity. In gradient backpropagation, SkipCut functions as a ShortCut, optimizing information flow and gradient allocation to enhance performance and accelerate training. Experiments on the RUOD dataset show that BSR5-integrated DETRs and YOLOs achieve state-of-the-art results for conventional and end-to-end detectors. Specifically, our BSR5-DETR improves 1.3% and 2.7% AP than RT-DETR with ResNet-101, while reducing parameters by 41.6% and 6.6%, respectively. Further validation highlights BSR5's strong convergence and robustness, especially in training from scratch scenarios, making it well suited for data-scarce, resource-constrained, and real-time tasks.

Underwater images often suffer from various issues such as low brightness, color shift, blurred details, and noise due to light absorption and scattering caused by water and suspended particles. Previous underwater image enhancement (UIE) methods have primarily focused on spatial domain enhancement, neglecting the frequency domain information inherent in the images. However, the degradation factors of underwater images are closely intertwined in the spatial domain. Although certain methods focus on enhancing images in the frequency domain, they overlook the inherent relationship between the image degradation factors and the information present in the frequency domain. As a result, these methods frequently enhance certain attributes of the improved image while inadequately addressing or even exacerbating other attributes. Moreover, many existing methods heavily rely on prior knowledge to address color shift problems in underwater images, limiting their flexibility and robustness. In order to overcome these limitations, we propose the Embedding Frequency and Dual Color Encoder Network (FDCE-Net) in our paper. The FDCE-Net consists of two main structures: 1) Frequency Spatial Network (FS-Net) aims to achieve initial enhancement by utilizing our designed Frequency Spatial Residual Block (FSRB) to decouple image degradation factors in the frequency domain and enhance different attributes separately; 2) To tackle the color shift issue, we introduce the Dual-Color Encoder (DCE). The DCE establishes correlations between color and semantic representations through cross-attention and leverages multi-scale image features to guide the optimization of adaptive color query. The final enhanced images are generated by combining the outputs of FS-Net and DCE through a fusion network. These images exhibit rich details, clear textures, low noise and natural colors. Extensive experiments demonstrate that our FDCE-Net outperforms state-of-the-art (SOTA) methods in terms of both visual quality and quantitative metrics. The code of our model is publicly available at:https://github.com/Alexande-rChan/FDCE-Net.

Color cast is one of the main degradations in underwater images. Existing data-driven methods, while capable of learning color correction rules from large datasets, often overlook the imaging characteristics and light behavior in underwater environments, making them unable to accurately restore colors in complex water bodies. To address this, we use color constancy and an underwater imaging model to heuristically model the underwater environment for accurate color restoration. On one hand, we propose a multi-scale joint prior network architecture to fully explore the rich feature-level information at different scales in underwater images. This is used to fit the complex parameters of the underwater imaging model, deriving high-quality potential undegraded images. On the other hand, to tackle the challenges of color distortion caused by complex imaging factors in different water environments, we estimate the background light of the water body through the color constancy of underwater objects and dynamically incorporate it into the underwater imaging model as a prior. This not only guides the learning process more effectively but also allows the model to consider key aspects of underwater optical propagation, making it adaptable to different water environments and improving the color accuracy of the enhanced images. We have also conducted extensive experiments to demonstrate the effectiveness of the proposed method, which not only achieves the best overall performance in qualitative analysis and quantitative comparison but also boasts the best color accuracy and the fastest inference speed. The code is available athttps://github.com/JunyuFan/MJPNet.

The absorption and scattering of light in the water medium naturally impair the quality of underwater images, leading to multiple degradation effects including color casts, reduced visibility, and blurriness. Underwater Image Enhancement (UIE) techniques strive to mitigate these issues, yet the efficacy of different UIE algorithms remains highly variable. This variability underscores the necessity for an objective quality metric capable of precisely assessing the visual quality of underwater images. Traditional quality metrics, which primarily rely on a single score to depict the overall quality level, are insufficiently comprehensive to describe the complex degradation characteristics intrinsic to underwater environments and the multi-dimensional nature of underwater image quality. To address this issue, we construct the first UIE quality evaluation dataset with multi-dimensional quality annotations, broadening the subjective labels from a single overall quality score to multiple specific degradation-related scores. The dataset is known as an enhanced version of our previous Subjectively Annotated UIE Benchmark Dataset (SAUD) and is called SAUD2.0 hereinafter. Based on the SAUD2.0 dataset, we also introduce a Multi-stream COllaborative LEarning network (MCOLE) tailored for quality evaluation of enhanced underwater images. MCOLE capitalizes on the multi-dimensional quality annotations within SAUD2.0, facilitating the training of three specialized networks focused on extracting distinct sets of features: color, visibility, and semantic. These extracted features are then interacted and cohesively merged for quality prediction. Comprehensive experiments conducted on two benchmark datasets reveal that the proposed MCOLE outperforms current underwater image quality metrics. These results clearly validate the efficacy of exploring the multi-dimensional nature of underwater image quality and integrating such multi-dimensional quality annotations into underwater image quality evaluation. Our dataset and code are available athttps://github.com/0117Tzx/MCOLE.

Remote sensing (RS) change detection (CD) faces challenges in effectively identifying non-salient change regions, such as subtle architectural modifications or changes that closely resemble the background. The primary difficulties stem from the weak feature representation of non-salient changes, which results in insufficient model response, and the high similarity between background and change regions, leading to misdetection or omission. To address this issue, we propose SPRMamba, a Mamba-based saliency proportion reconciliatory network with squeezed windows for remote sensing change detection. It introduces state space models with windowing operations and cross-window interaction mechanisms to improve the response to weak signals. To dynamically balance the representation of salient and non-salient features, we design the saliency proportion reconciler (SPR) to optimize the discrimination between background and change regions. In addition, we introduce a sparse saliency loss function, which imposes sparsity constraints on salient regions to enhance the feature representation of non-salient change regions. Experimental results show that SPRMamba significantly outperforms existing methods on several public datasets. Our code will be available at https://github.com/boomstarzzn/SPRMamba.

Underwater imaging is essential for marine remote sensing tasks, such as environmental monitoring, resource exploration, and autonomous navigation. However, images captured in underwater environments often suffer from complex degradations, including wavelength-dependent color distortion, contrast attenuation, and structural detail loss. To address these challenges, we propose a Cross-Scale Style-Guided Network (CSG-Net) for robust underwater image enhancement. CSG-Net employs a dual-stage collaborative framework that decouples global degradation modeling from local detail refinement. In the first stage, a Style Extraction Network (SE-Net) extracts multi-scale degradation-aware style priors that implicitly encode large-scale physical degradation patterns, such as red-channel attenuation and spectral imbalance. In the second stage, a Style-Guided Enhancement Network (SG-Net) leverages these style features to guide spatially adaptive enhancement, enabling consistent color correction and fine-grained detail recovery. To alleviate semantic degradation during scale transitions, CSG-Net introduces the proposed multi-resolution feature-preserving cross-scale interaction (MFPCSI) module, which enhances the preservation and integration of hierarchical features. Combined with the Multi-Stream Information Fusion (MSIF) module, this design enables the effective fusion of semantic and structural information across spatial scales. The proposed components enable the preservation of fine-grained details while adaptively integrating semantic and structural cues across multiple scales. Comprehensive experiments conducted on diverse and challenging underwater image datasets demonstrate that CSG-Net consistently surpasses state-of-the-art approaches in terms of PSNR, SSIM, and UIQM. Furthermore, the model exhibits strong cross-domain generalization and delivers high-fidelity visual results, underscoring its suitability for deployment in practical vision systems operating under complex, real-world environments.

Underwater data is inherently scarce and exhibits complex distributions, making it challenging to train high-performance models from scratch. In contrast, in-air models are structurally mature, resource-rich, and offer strong potential for transfer. However, significant discrepancies in visual characteristics and feature distributions between underwater and in-air environments often lead to severe performance degradation when applying in-air models directly. To address this issue, we propose IA2U, a lightweight plugin designed for efficient underwater adaptation without modifying the original model architecture. IA2U can be flexibly integrated into arbitrary in-air networks, offering high generalizability and low deployment costs. Specifically, IA2U incorporates three types of prior knowledge-water type, degradation pattern, and sample semantics-which are embedded into intermediate layers through feature injection and channel-wise modulation to guide the network's response to underwater-specific features. Furthermore, a multi-scale feature alignment module is introduced to dynamically balance information across different resolution paths, enhancing consistency and contextual representation. Extensive experiments demonstrate that IA2U significantly improves both image enhancement and object detection performance. Specifically, on the UIEB dataset, IA2U boosts Shallow-UWNet by 5.2 dB in PSNR and reduces LPIPS by 52%; on the RUOD dataset, it increases AP by 1.8% when applied to the PAA detector. IA2U provides an effective and scalable solution for building robust underwater perception systems with minimal adaptation costs. Our code is available at https://github.com/zhoujingchun03/IA2U.

Underwater image enhancement (UIE) is a highly challenging task due to the complexity of underwater environment and the diversity of underwater image degradation. Due to the application of deep learning, current UIE methods have made significant progress. Most of the existing deep learning-based UIE methods follow a single-stage network which cannot effectively address the diverse degradations simultaneously. In this paper, we propose to address this issue by designing a two-stage deep learning framework and taking advantage of cascaded contrastive learning to guide the network training of each stage. The proposed method is called CCL-Net in short. Specifically, the proposed CCL-Net involves two cascaded stages, i.e., a color correction stage tailored to the color deviation issue and a haze removal stage tailored to improve the visibility and contrast of underwater images. To guarantee the underwater image can be progressively enhanced, we also apply contrastive loss as an additional constraint to guide the training of each stage. In the first stage, the raw underwater images are used as negative samples for building the first contrastive loss, ensuring the enhanced results of the first color correction stage are better than the original inputs. While in the second stage, the enhanced results rather than the raw underwater images of the first color correction stage are used as the negative samples for building the second contrastive loss, thus ensuring the final enhanced results of the second haze removal stage are better than the intermediate color corrected results. Extensive experiments on multiple benchmark datasets demonstrate that our CCL-Net can achieve superior performance compared to many state-of-the-art methods. In addition, a series of ablation studies also verify the effectiveness of each key component involved in the proposed CCL-Net.

Underwater image quality assessment (UIQA) is a challenging task due to the complexities of underwater environments. Traditional UIQA methods primarily rely on fitting mean opinion scores (MOS), which are limited by human visual biases. To address the above limitation, we propose a no-reference underwater image quality assessment paradigm using reinforcement sequences. Our paradigm leverages reinforcement learning to iteratively merge the input image with the corresponding ground truth, generating an optimized sequence of images. A classifier generates probability arrays for the optimized sequence, which are converted into objective scores by a regression model. Unlike existing methods that focus solely on the final quality score, our paradigm emphasizes dynamic quality changes throughout the image-enhancement process. By employing objective mixing ratio labels, our reinforcement sequence dataset reduces subjective bias. The multiscale classifier captures local and global information differences between the input and ground truth images, effectively preserving the contrast and detail in diverse lighting conditions. Our paradigm combines multi-source data classification with support vector regression, optimizing the mapping of feature vectors to quality scores through fine-tuning libsvm kernel parameters. Experimental results on multiple benchmark datasets demonstrate that our paradigm outperforms the state-of-the-art UIQA methods, providing an effective solution for Underwater Image quality Assessment via Reinforcement Sequences (RSUIA).

Visually restoring underwater scenes primarily involves mitigating interference from underwater media. Existing methods ignore the inherent scale-related characteristics in underwater scenes. Therefore, we present the synergistic multi-scale detail refinement via intrinsic supervision (SMDR-IS) for enhancing underwater scene details, which contain multi-stages. The low-degradation stage from the original images furnishes the original stage with multi-scale details, achieved through feature propagation using the Adaptive Selective Intrinsic Supervised Feature (ASISF) module. By using intrinsic supervision, the ASISF module can precisely control and guide feature transmission across multi-degradation stages, enhancing multi-scale detail refinement and minimizing the interference from irrelevant information in the low-degradation stage. In multi-degradation encoder-decoder framework of SMDR-IS, we introduce the Bifocal Intrinsic-Context Attention Module (BICA). Based on the intrinsic supervision principles, BICA efficiently exploits multi-scale scene information in images. BICA directs higher-resolution spaces by tapping into the insights of lower-resolution ones, underscoring the pivotal role of spatial contextual relationships in underwater image restoration. Throughout training, the inclusion of a multi-degradation loss function can enhance the network, allowing it to adeptly extract information across diverse scales. When benchmarked against state-of-the-art methods, SMDR-IS consistently showcases superior performance. Our code is available at https://github.com/zhoujingchun03/SMDR-IS

In this paper, we present a novel Amplitude-Modulated Stochastic Perturbation and Vortex Convolutional Network, AMSP-UOD, designed for underwater object detection. AMSP-UOD specifically addresses the impact of non-ideal imaging factors on detection accuracy in complex underwater environments. To mitigate the influence of noise on object detection performance, we propose AMSP Vortex Convolution (AMSP-VConv) to disrupt the noise distribution, enhance feature extraction capabilities, effectively reduce parameters, and improve network robustness. We design the Feature Association Decoupling Cross Stage Partial (FAD-CSP) module, which strengthens the association of long and short range features, improving the network performance in complex underwater environments. Additionally, our sophisticated post-processing method, based on non-maximum suppression with aspect-ratio similarity thresholds, optimizes detection in dense scenes, such as waterweed and schools of fish, improving object detection accuracy. Extensive experiments on the URPC and RUOD datasets demonstrate that our method outperforms existing state-of-the-art methods in terms of accuracy and noise immunity. AMSP-UOD proposes an innovative solution with the potential for real-world applications. Our code is available at https://github.com/zhoujingchun03/AMSP-UOD.

Underwater image enhancement presents a significant challenge due to the complex and diverse underwater environments that result in severe degradation phenomena such as light absorption, scattering, and color distortion. More importantly, obtaining paired training data for these scenarios is a challenging task, which further hinders the generalization performance of enhancement models. To address these issues, we propose a novel approach, the Hybrid Contrastive Learning Regularization (HCLR-Net). Our method is built upon a distinctive hybrid contrastive learning regularization strategy that incorporates a unique methodology for constructing negative samples. This approach enables the network to develop a more robust sample distribution. Notably, we utilize non-paired data for both positive and negative samples, with negative samples are innovatively reconstructed using local patch perturbations. This strategy overcomes the constraints of relying solely on paired data, boosting the model’s potential for generalization. The HCLR-Net also incorporates an Adaptive Hybrid Attention module and a Detail Repair Branch for effective feature extraction and texture detail restoration, respectively. Comprehensive experiments demonstrate the superiority of our method, which shows substantial improvements over several state-of-the-art methods in terms of quantitative metrics, significantly enhances the visual quality of underwater images, establishing its innovative and practical applicability. Our code is available at: https://github.com/zhoujingchun03/HCLR-Net .

Anchor-free object detectors have recently received increasing research attention in the field of aerial scene object detection, due to their high flexibility and practicality. Anchor-free detectors typically depend on the feature pyramid network (FPN) to alleviate the challenge of significant variations in object scales in aerial contexts. Despite establishing a multi-scale feature pyramid, existing FPN-based methods treat each aerial object as an indivisible entity solely managed by a single-scale representation. However, they fail to take into account the distinct characteristics of various components within an instance. To this end, this letter proposes a novel anchor-free detector, namely IMPR-Det, which can integrally mix multi-scale pyramid representations for different components of an instance, thus boosting the fine-grained object representation capability. Specifically, IMPR-Det fundamentally introduces a more advanced detection head with an adaptive routing mechanism for pixel-level multi-scale feature assignment, instead of previous instance-level assignment. Experimental results demonstrate the superiority of the proposed method over its counterparts, in terms of both accuracy and efficiency, for object detection in aerial images.

Enhancing underwater images captured under mixed artificial and natural lighting conditions presents two critical challenges. Existing methods lack a unified luminance feature extraction paradigm for mixed lighting scenes, leading to imbalance in luminance features, and consequent local overexposure or underexposure. Additionally, some color correction methods, through the fusion of features across multiple color spaces neglect the information loss due to the absence of feature alignment in cross-space fusion. To address these challenges, we propose a specialized method, namely IACC, which unifies the luminance features of underwater images under mixed lighting and guides consistent enhancement across similar luminance regions. Furthermore, complementary colors are introduced to globally guide the correction of color discrepancies, preserving the structural consistency and mitigating potential structural information loss during the original image feature extraction. Extensive experiments on various underwater datasets demonstrate the superiority of our method, which outperforms state-of-the-art methods in both machine and human visual perception. Our code is available athttps://github.com/zhoujingchun03/IACC.

Water-related optics images are often degraded by absorption and scattering effects. Current underwater image enhancement (UIE) methods improve image quality but neglect the constraints of underwater imaging environments. To address this issue, we propose a double-teacher knowledge distilling network (DTKD-Net), which uses a dynamic teaching strategy within a dual-teacher framework to enhance knowledge distillation (KD), improving the student network’s ability to capture complex underwater features. Specifically, DTKD-Net focuses on clear-to-clear and blurry-to-clear image learning to enhance underwater images. It aims to preserve details in clear images and restore blurred ones. The dual-teacher network uses an intermediate layer with the middle layer of the student network to compute feature differences for feature guidance. The network uses a dynamic strategy where a Teacher-Sub stops guidance when its output matches the student’s, which helps with contrastive learning and improves the network’s ability to handle complex underwater scenes. Extensive experiments and visual comparisons show that DTKD-Net reduces the model size, demonstrating superior efficiency and effectiveness in enhancing underwater images.

High-quality underwater imaging is crucial for underwater exploration. However, particle scattering and light absorption by seawater significantly degrade image clarity. To address these issues, we propose a novel underwater image enhancement (UIE) method that combines pixel distribution remapping (PDR) with a multi-priority Retinex variational model. We design a pre-compensation method for severely attenuated channels that effectively prevents new color artifacts during color correction. By combining the inter-channel coupling relationships, we compute a limiting factor to remap pixel distribution curves to improve image contrast. In addition, considering the significant noise interference, we introduce the prior knowledge, including underwater noise and texture priors, while constructing the variational model, and design penalty terms that match the underwater characteristics to remove excessive noise in the reflectance component. Our approach efficiently decouples the illumination and reflectance components using a rapid solver. Subsequently, gamma correction adjusts the illumination component, and the corrected illumination and reflectance components are fused to reconstruct the final natural output image. Comprehensive evaluations across various datasets reveal that our approach significantly surpasses current state-of-the-art (SOTA) methods. These results demonstrate the effectiveness of our method in correcting color bias and compensating for luminance losses in underwater imagery. Our code is available at:https://github.com/zhoujingchun03/PDRMRV.

Modern underwater object detection methods recognize objects from sonar data based on their geometric shapes. However, the distortion of objects during data acquisition and representation is seldom considered. In this paper, we present a detailed summary of representations for sonar data and a concrete analysis of the geometric characteristics of different data representations. Based on this, a feature fusion framework is proposed to fully use the intensity features extracted from the polar image representation and the geometric features learned from the point cloud representation of sonar data. Three feature fusion strategies are presented to investigate the impact of feature fusion on different components of the detection pipeline. In addition, the fusion strategies can be easily integrated into other detectors, such as the You Only Look Once (YOLO) series. The effectiveness of our proposed framework and feature fusion strategies is demonstrated on a public sonar dataset captured in real-world underwater environments. Experimental results show that our method benefits both the region proposal and the object classification modules in the detectors.

Light traveling through water results in strong scattering across color channels, restricting visibility in underwater images. Many cutting-edge underwater image enhancement methods encounter limitations in color recovery accuracy and resilience against irrelevant feature interference. To tackle these degradation challenges, we propose an efficient and fully guided information flow network called UGIF-Net, for enhancing underwater images. Specifically, we propose a multi-color space-guided color estimation module that accurately approximates color information by incorporating features from two color spaces within a unified network. Subsequently, we employ a dense attention block to guide the network in thoroughly extracting color information from both color spaces while adaptively perceiving crucial color information. Moreover, we devise a color-guided map to steer the network’s focus toward color information and augment its response to color quality degradation. We incorporate the guided map into a guide color restoration module to achieve visually appealing enhancement results. Comprehensive experiments indicate that our approach surpasses state-of-the-art methods, showcasing favorable image restoration effects and their potential to aid other high-level vision tasks.

The red spectrum is saliently attenuated due to the absorption and scattering properties of water. The acquired underwater images show severe color cast in underwater scenes. In this letter, we propose a novel color correction method for underwater images, which removes color cast on single pixels based on scene depth. The experimental results demonstrate that our approach can significantly improve the color effect and provide a correct input for the subsequent underwater image defogging methods.

In underwater scenes, the quality of the video and image acquired by the underwater imaging system suffers from severe degradation, influencing target detection and recognition. Thus, restoring real scenes from blurred videos and images is of great significance. Owing to the light absorption and scattering by suspended particles, the images acquired often have poor visibility, including color shift, low contrast, noise, and blurring issues. This paper aims to classify and compare some of the significant technologies in underwater image defogging, presenting a comprehensive picture of the current research landscape for researchers. First we analyze the reasons for degradation of underwater images and the underwater optical imaging model. Then we classify the underwater image defogging technologies into three categories, including image restoration approaches, image enhancement approaches, and deep learning approaches. Afterward, we present the objective evaluation metrics and analyze the state-of-the-art approaches. Finally, we summarize the shortcomings of the defogging approaches for underwater images and propose seven research directions.