我们从一组未配对的清晰和朦胧的图像中提供了实用的基于学习的图像飞行网络。本文提供了一种新的观点，可以将图像除去作为两类分离的因子分离任务，即清晰图像重建的任务相关因素以及与雾霾相关的分布的任务含量。为了在深度特征空间中实现这两类因素的分离，将对比度学习引入了一个自行车框架中，以通过指导与潜在因素相关的生成的图像来学习分离的表示形式。通过这种表述，提出的对比度拆除的脱掩护方法（CDD-GAN）采用负面发电机与编码器网络合作以交替进行更新，以产生挑战性负面对手的队列。然后，这些负面的对手是端到端训练的，以及骨干代表网络，以通过最大化对抗性对比损失来增强歧视性信息并促进因素分离性能。在培训期间，我们进一步表明，硬性负面例子可以抑制任务 - 无关紧要的因素和未配对的清晰景象可以增强与任务相关的因素，以便更好地促进雾霾去除并帮助图像恢复。对合成和现实世界数据集的广泛实验表明，我们的方法对现有的未配对飞行基线的表现良好。

With the development of convolutional neural networks, hundreds of deep learning based dehazing methods have been proposed. In this paper, we provide a comprehensive survey on supervised, semi-supervised, and unsupervised single image dehazing. We first discuss the physical model, datasets, network modules, loss functions, and evaluation metrics that are commonly used. Then, the main contributions of various dehazing algorithms are categorized and summarized. Further, quantitative and qualitative experiments of various baseline methods are carried out. Finally, the unsolved issues and challenges that can inspire the future research are pointed out. A collection of useful dehazing materials is available at \url{https://github.com/Xiaofeng-life/AwesomeDehazing}.

Image restoration under hazy weather condition, which is called single image dehazing, has been of significant interest for various computer vision applications. In recent years, deep learning-based methods have achieved success. However, existing image dehazing methods typically neglect the hierarchy of features in the neural network and fail to exploit their relationships fully. To this end, we propose an effective image dehazing method named Hierarchical Contrastive Dehazing (HCD), which is based on feature fusion and contrastive learning strategies. HCD consists of a hierarchical dehazing network (HDN) and a novel hierarchical contrastive loss (HCL). Specifically, the core design in the HDN is a Hierarchical Interaction Module, which utilizes multi-scale activation to revise the feature responses hierarchically. To cooperate with the training of HDN, we propose HCL which performs contrastive learning on hierarchically paired exemplars, facilitating haze removal. Extensive experiments on public datasets, RESIDE, HazeRD, and DENSE-HAZE, demonstrate that HCD quantitatively outperforms the state-of-the-art methods in terms of PSNR, SSIM and achieves better visual quality.

Segmenting the fine structure of the mouse brain on magnetic resonance (MR) images is critical for delineating morphological regions, analyzing brain function, and understanding their relationships. Compared to a single MRI modality, multimodal MRI data provide complementary tissue features that can be exploited by deep learning models, resulting in better segmentation results. However, multimodal mouse brain MRI data is often lacking, making automatic segmentation of mouse brain fine structure a very challenging task. To address this issue, it is necessary to fuse multimodal MRI data to produce distinguished contrasts in different brain structures. Hence, we propose a novel disentangled and contrastive GAN-based framework, named MouseGAN++, to synthesize multiple MR modalities from single ones in a structure-preserving manner, thus improving the segmentation performance by imputing missing modalities and multi-modality fusion. Our results demonstrate that the translation performance of our method outperforms the state-of-the-art methods. Using the subsequently learned modality-invariant information as well as the modality-translated images, MouseGAN++ can segment fine brain structures with averaged dice coefficients of 90.0% (T2w) and 87.9% (T1w), respectively, achieving around +10% performance improvement compared to the state-of-the-art algorithms. Our results demonstrate that MouseGAN++, as a simultaneous image synthesis and segmentation method, can be used to fuse cross-modality information in an unpaired manner and yield more robust performance in the absence of multimodal data. We release our method as a mouse brain structural segmentation tool for free academic usage at https://github.com/yu02019.

In image-to-image translation, each patch in the output should reflect the content of the corresponding patch in the input, independent of domain. We propose a straightforward method for doing so -maximizing mutual information between the two, using a framework based on contrastive learning. The method encourages two elements (corresponding patches) to map to a similar point in a learned feature space, relative to other elements (other patches) in the dataset, referred to as negatives. We explore several critical design choices for making contrastive learning effective in the image synthesis setting. Notably, we use a multilayer, patch-based approach, rather than operate on entire images. Furthermore, we draw negatives from within the input image itself, rather than from the rest of the dataset. We demonstrate that our framework enables one-sided translation in the unpaired image-to-image translation setting, while improving quality and reducing training time. In addition, our method can even be extended to the training setting where each "domain" is only a single image.

基于深度学习的低光图像增强方法通常需要巨大的配对训练数据，这对于在现实世界的场景中捕获是不切实际的。最近，已经探索了无监督的方法来消除对成对训练数据的依赖。然而，由于没有前衣，它们在不同的现实情景中表现得不稳定。为了解决这个问题，我们提出了一种基于先前（HEP）的有效预期直方图均衡的无监督的低光图像增强方法。我们的作品受到了有趣的观察，即直方图均衡增强图像的特征图和地面真理是相似的。具体而言，我们制定了HEP，提供了丰富的纹理和亮度信息。嵌入一​​个亮度模块（LUM），它有助于将低光图像分解为照明和反射率图，并且反射率图可以被视为恢复的图像。然而，基于Retinex理论的推导揭示了反射率图被噪声污染。我们介绍了一个噪声解剖学模块（NDM），以解除反射率图中的噪声和内容，具有不配对清洁图像的可靠帮助。通过直方图均衡的先前和噪声解剖，我们的方法可以恢复更精细的细节，更有能力抑制现实世界低光场景中的噪声。广泛的实验表明，我们的方法对最先进的无监督的低光增强算法有利地表现出甚至与最先进的监督算法匹配。

对比学习在各种高级任务中取得了显着的成功，但是为低级任务提出了较少的方法。采用VANILLA对比学习技术采用直接为低级视觉任务提出的VANILLA对比度学习技术，因为所获得的全局视觉表现不足以用于需要丰富的纹理和上下文信息的低级任务。在本文中，我们提出了一种用于单图像超分辨率（SISR）的新型对比学习框架。我们从两个视角调查基于对比的学习的SISR：样品施工和特征嵌入。现有方法提出了一些天真的样本施工方法（例如，考虑到作为负样本的低质量输入以及作为正样品的地面真理），并且它们采用了先前的模型（例如，预先训练的VGG模型）来获得该特征嵌入而不是探索任务友好的。为此，我们向SISR提出了一个实用的对比学习框架，涉及在频率空间中产生许多信息丰富的正负样本。我们不是利用其他预先训练的网络，我们设计了一种从鉴别器网络继承的简单但有效的嵌入网络，并且可以用主SR网络迭代优化，使其成为任务最通报。最后，我们对我们的方法进行了广泛的实验评估，与基准方法相比，在目前的最先进的SISR方法中显示出高达0.21 dB的显着增益。

基于对抗性学习的图像抑制方法，由于其出色的性能，已经在计算机视觉中进行了广泛的研究。但是，大多数现有方法对实际情况的质量功能有限，因为它们在相同场景的透明和合成的雾化图像上进行了培训。此外，它们在保留鲜艳的色彩和丰富的文本细节方面存在局限性。为了解决这些问题，我们开发了一个新颖的生成对抗网络，称为整体注意力融合对抗网络（HAAN），用于单个图像。 Haan由Fog2FogFogre块和FogFree2Fog块组成。在每个块中，有三个基于学习的模块，即雾除雾，颜色纹理恢复和雾合成，它们相互限制以生成高质量的图像。 Haan旨在通过学习雾图图像之间的整体通道空间特征相关性及其几个派生图像之间的整体通道空间特征相关性来利用纹理和结构信息的自相似性。此外，在雾合成模块中，我们利用大气散射模型来指导它，以通过新颖的天空分割网络专注于大气光优化来提高生成质量。关于合成和现实世界数据集的广泛实验表明，就定量准确性和主观的视觉质量而言，Haan的表现优于最先进的脱落方法。

在低灯条件下捕获的图像遭受低可视性和各种成像伪影，例如真实噪音。现有的监督启示算法需要大量的像素对齐的训练图像对，这很难在实践中准备。虽然弱监督或无人监督的方法可以缓解这些挑战，但不使用配对的训练图像，由于缺乏相应的监督，一些现实世界的文物不可避免地被错误地放大。在本文中，而不是使用完美的对齐图像进行培训，我们创造性地使用未对准的现实世界图像作为指导，这很容易收集。具体地，我们提出了一个交叉图像解剖线程（CIDN），以分别提取来自低/常光图像的交叉图像亮度和图像特定内容特征。基于此，CIDN可以同时校正特征域中的亮度和抑制图像伪像，其在很大程度上将鲁棒性增加到像素偏移。此外，我们收集了一个新的低光图像增强数据集，包括具有现实世界腐败的未对准培训图像。实验结果表明，我们的模型在新建议的数据集和其他流行的低光数据集中实现了最先进的表演。

Deep Convolutional Neural Networks (DCNNs) have exhibited impressive performance on image super-resolution tasks. However, these deep learning-based super-resolution methods perform poorly in real-world super-resolution tasks, where the paired high-resolution and low-resolution images are unavailable and the low-resolution images are degraded by complicated and unknown kernels. To break these limitations, we propose the Unsupervised Bi-directional Cycle Domain Transfer Learning-based Generative Adversarial Network (UBCDTL-GAN), which consists of an Unsupervised Bi-directional Cycle Domain Transfer Network (UBCDTN) and the Semantic Encoder guided Super Resolution Network (SESRN). First, the UBCDTN is able to produce an approximated real-like LR image through transferring the LR image from an artificially degraded domain to the real-world LR image domain. Second, the SESRN has the ability to super-resolve the approximated real-like LR image to a photo-realistic HR image. Extensive experiments on unpaired real-world image benchmark datasets demonstrate that the proposed method achieves superior performance compared to state-of-the-art methods.

Deep learning-based methods have achieved significant performance for image defogging. However, existing methods are mainly developed for land scenes and perform poorly when dealing with overwater foggy images, since overwater scenes typically contain large expanses of sky and water. In this work, we propose a Prior map Guided CycleGAN (PG-CycleGAN) for defogging of images with overwater scenes. To promote the recovery of the objects on water in the image, two loss functions are exploited for the network where a prior map is designed to invert the dark channel and the min-max normalization is used to suppress the sky and emphasize objects. However, due to the unpaired training set, the network may learn an under-constrained domain mapping from foggy to fog-free image, leading to artifacts and loss of details. Thus, we propose an intuitive Upscaling Inception Module (UIM) and a Long-range Residual Coarse-to-fine framework (LRC) to mitigate this issue. Extensive experiments on qualitative and quantitative comparisons demonstrate that the proposed method outperforms the state-of-the-art supervised, semi-supervised, and unsupervised defogging approaches.

雨是最常见的天气之一，可以完全降低图像质量并干扰许多计算机视觉任务的执行，尤其是在大雨条件下。我们观察到：（i）雨是雨水和雨淋的混合物； （ii）场景的深度决定了雨条的强度以及变成多雨的阴霾的强度； （iii）大多数现有的DERANE方法仅在合成雨图像上进行训练，因此对现实世界的场景概括不佳。在这些观察结果的激励下，我们提出了一种新的半监督，清除降雨生成的对抗网络（半密集），该混合物由四个关键模块组成：（i）新的注意力深度预测网络以提供精确的深度估计； （ii）上下文特征预测网络由几个精心设计的详细残留块组成，以产生详细的图像上下文特征； （iii）金字塔深度引导的非本地网络，以有效地将图像上下文与深度信息整合在一起，并产生最终的无雨图像； （iv）全面的半监督损失函数，使该模型不限于合成数据集，而是平稳地将其概括为现实世界中的大雨场景。广泛的实验表明，在合成和现实世界中，我们的二十多种代表性的最先进的方法对我们的方法进行了明显的改进。

生成的对抗网络（GAN）已受过培训，成为能够创作出令人惊叹的艺术品（例如面部生成和图像样式转移）的专业艺术家。在本文中，我们专注于现实的业务方案：具有所需的移动应用程序和主题样式的可自定义图标的自动生成。我们首先引入一个主题应用图标数据集，称为Appicon，每个图标都有两个正交主题和应用标签。通过研究强大的基线样式，我们观察到由正交标签的纠缠引起的模式崩溃。为了解决这一挑战，我们提出了由有条件的发电机和双重歧视器组成的ICONGAN，具有正交扩大，并且进一步设计了对比的特征分离策略，以使两个歧视器的特征空间正常。与其他方法相比，ICONGAN在Appicon基准测试中表明了优势。进一步的分析还证明了解开应用程序和主题表示的有效性。我们的项目将在以下网址发布：https：//github.com/architect-road/icongan。

盲目图像脱毛（BID）仍然是一项具有挑战性且重大的任务。从深度学习的强大合适能力中受益，成对的数据驱动的监督竞标方法取得了巨大进展。但是，配对数据通常是手工合成的，现实的模糊比合成数据更复杂，这使得监督的方法无能为力地建模现实的模糊和阻碍其现实世界的应用。因此，没有配对数据的无监督的深入竞标方法提供了某些优势，但是当前的方法仍然存在一些缺点，例如笨重的模型大小，较长的推理时间以及严格的图像分辨率和域要求。在本文中，我们提出了一个轻巧和实时的无监督的投标基线，称为频域对比度损失约束的轻质自行车（不久，fcl-gan），具有吸引人的特性，即无图像域限制，无图像分辨率限制，25x，25x比SOTA轻，比Sota快5倍。为了确保轻巧的属性和性能优势，设计了两个新的合作单元，称为轻量级域转换单元（LDCU）和无参数频域对比单元（PFCU）。 LDCU主要以轻质方式实现域间转换。 PFCU进一步探讨了频域中模糊域和尖锐域图像之间的相似性度量，外部差异和内部连接，而无需涉及额外的参数。在几个图像数据集上进行的广泛实验证明了我们的FCL-GAN在性能，模型大小和参考时间方面的有效性。

深度学习算法最近在自然和合成的多雨数据集中达到了有希望的污染性能。作为必不可少的低级预处理阶段，派威网络应清除雨条纹并保留精细的语义细节。但是，大多数现有方法只考虑低级图像恢复。这限制了它们在需要精确语义信息的高级任务中的表现。为了解决这个问题，在本文中，我们基于对单个图像放置的对比学习来呈现分段感知逐行网络（SAPNET）。我们开始使用具有渐进扩张单元（PDU）的轻量级污染网络（PDU）。 PDU可以显着扩展接收领域，并在没有对多尺度图像上的沉重计算的情况下表征多尺度雨条纹。这项工作的一个基本方面是一个无人监督的背景分割（UBS）网络用Imagenet和高斯权重初始化。瑞银可以忠实地保留图像的语义信息，并改善解释照片的概括能力。此外，我们介绍了一种感知对比丧失（PCL）和学习的感知图像相似性损失（LPIS）来调节模型学习。通过利用雨天图像和地面，作为VGG-16潜在空间中的负片和正样品，我们以完全约束的方式弥合托盘图像和地面的微妙语义细节。综合性和现实世界多雨图像的综合实验显示我们的模型超越了顶级性能的方法，并具有相当大的疗效。 pytorch实现可在https://github.com/shenzheng2000/sapnet-for-image -dering。

受监管的基于学习的方法屈服于强大的去噪结果，但它们本质上受到大规模清洁/嘈杂配对数据集的需要。另一方面，使用无监督的脱言机需要更详细地了解潜在的图像统计数据。特别是，众所周知，在高频频带上，清洁和嘈杂的图像之间的表观差异是最突出的，证明使用低通滤波器作为传统图像预处理步骤的一部分。然而，基于大多数基于学习的去噪方法在不考虑频域信息的情况下仅利用来自空间域的片面信息。为了解决这一限制，在本研究中，我们提出了一种频率敏感的无监督去噪方法。为此，使用生成的对抗性网络（GaN）作为基础结构。随后，我们包括光谱鉴别器和频率重建损失，以将频率知识传输到发电机中。使用自然和合成数据集的结果表明，我们无监督的学习方法增强了频率信息，实现了最先进的去噪能力，表明频域信息可能是提高无监督基于学习的方法的整体性能的可行因素。

通过对抗训练的雾霾图像转换的关键程序在于仅涉及雾度合成的特征，即表示不变语义内容的特征，即内容特征。以前的方法通过利用它在培训过程中对Haze图像进行分类来分开单独的内容。然而，在本文中，我们认识到在这种技术常规中的内容式解剖学的不完整性。缺陷的样式功能与内容信息纠缠不可避免地引导阴霾图像的呈现。要解决，我们通过随机线性插值提出自我监督的风格回归，以减少风格特征中的内容信息。烧蚀实验表明了静态感知雾度图像合成中的解开的完整性及其优越性。此外，所产生的雾度数据应用于车辆检测器的测试概括。雾度和检测性能之间的进一步研究表明，雾度对车辆探测器的概括具有明显的影响，并且这种性能降低水平与雾度水平线性相关，反过来验证了该方法的有效性。

Automatic font generation without human experts is a practical and significant problem, especially for some languages that consist of a large number of characters. Existing methods for font generation are often in supervised learning. They require a large number of paired data, which are labor-intensive and expensive to collect. In contrast, common unsupervised image-to-image translation methods are not applicable to font generation, as they often define style as the set of textures and colors. In this work, we propose a robust deformable generative network for unsupervised font generation (abbreviated as DGFont++). We introduce a feature deformation skip connection (FDSC) to learn local patterns and geometric transformations between fonts. The FDSC predicts pairs of displacement maps and employs the predicted maps to apply deformable convolution to the low-level content feature maps. The outputs of FDSC are fed into a mixer to generate final results. Moreover, we introduce contrastive self-supervised learning to learn a robust style representation for fonts by understanding the similarity and dissimilarities of fonts. To distinguish different styles, we train our model with a multi-task discriminator, which ensures that each style can be discriminated independently. In addition to adversarial loss, another two reconstruction losses are adopted to constrain the domain-invariant characteristics between generated images and content images. Taking advantage of FDSC and the adopted loss functions, our model is able to maintain spatial information and generates high-quality character images in an unsupervised manner. Experiments demonstrate that our model is able to generate character images of higher quality than state-of-the-art methods.

图像平滑是一项基本的低级视觉任务，旨在保留图像的显着结构，同时删除微不足道的细节。图像平滑中已经探索了深度学习，以应对语义结构和琐碎细节的复杂纠缠。但是，当前的方法忽略了平滑方面的两个重要事实：1）受限数量的高质量平滑地面真相监督的幼稚像素级回归可能会导致域的转移，并导致对现实世界图像的概括问题； 2）纹理外观与对象语义密切相关，因此图像平滑需要意识到语义差异以应用自适应平滑强度。为了解决这些问题，我们提出了一个新颖的对比语义引导的图像平滑网络（CSGIS-NET），该网络在促进强大的图像平滑之前结合了对比的先验和语义。通过利用不希望的平滑效应作为负面教师，并结合分段任务以鼓励语义独特性来增强监督信号。为了实现所提出的网络，我们还使用纹理增强和平滑标签（即VOC-Smooth）丰富了原始的VOC数据集，它们首先桥接图像平滑和语义分割。广泛的实验表明，所提出的CSGI-NET大量优于最先进的算法。代码和数据集可在https://github.com/wangjie6866/csgis-net上找到。

Face Restoration (FR) aims to restore High-Quality (HQ) faces from Low-Quality (LQ) input images, which is a domain-specific image restoration problem in the low-level computer vision area. The early face restoration methods mainly use statistic priors and degradation models, which are difficult to meet the requirements of real-world applications in practice. In recent years, face restoration has witnessed great progress after stepping into the deep learning era. However, there are few works to study deep learning-based face restoration methods systematically. Thus, this paper comprehensively surveys recent advances in deep learning techniques for face restoration. Specifically, we first summarize different problem formulations and analyze the characteristic of the face image. Second, we discuss the challenges of face restoration. Concerning these challenges, we present a comprehensive review of existing FR methods, including prior based methods and deep learning-based methods. Then, we explore developed techniques in the task of FR covering network architectures, loss functions, and benchmark datasets. We also conduct a systematic benchmark evaluation on representative methods. Finally, we discuss future directions, including network designs, metrics, benchmark datasets, applications,etc. We also provide an open-source repository for all the discussed methods, which is available at https://github.com/TaoWangzj/Awesome-Face-Restoration.