Generative models have been very successful over the years and have received significant attention for synthetic data generation. As deep learning models are getting more and more complex, they require large amounts of data to perform accurately. In medical image analysis, such generative models play a crucial role as the available data is limited due to challenges related to data privacy, lack of data diversity, or uneven data distributions. In this paper, we present a method to generate brain tumor MRI images using generative adversarial networks. We have utilized StyleGAN2 with ADA methodology to generate high-quality brain MRI with tumors while using a significantly smaller amount of training data when compared to the existing approaches. We use three pre-trained models for transfer learning. Results demonstrate that the proposed method can learn the distributions of brain tumors. Furthermore, the model can generate high-quality synthetic brain MRI with a tumor that can limit the small sample size issues. The approach can addresses the limited data availability by generating realistic-looking brain MRI with tumors. The code is available at: ~\url{https://github.com/rizwanqureshi123/Brain-Tumor-Synthetic-Data}.

基于深度学习的计算机辅助诊断（CAD）已成为医疗行业的重要诊断技术，有效提高诊断精度。然而，脑肿瘤磁共振（MR）图像数据集的稀缺性导致深度学习算法的低性能。传统数据增强（DA）生成的转换图像的分布本质上类似于原始的图像，从而在泛化能力方面产生有限的性能。这项工作提高了具有结构相似性损失功能（PGGAN-SSIM）的GAN的逐步生长，以解决图像模糊问题和模型崩溃。我们还探讨了其他基于GAN的数据增强，以证明所提出的模型的有效性。我们的结果表明，PGGAN-SSIM成功地生成了256x256的现实脑肿瘤MR图像，填充了原始数据集未发现的真实图像分布。此外，PGGAN-SSSIM超过了其他基于GAN的方法，实现了FRECHET成立距离（FID）和多尺度结构相似性（MS-SSIM）的有希望的性能提升。

三维（3D）医学图像的产生可能具有巨大的应用潜力，因为它考虑了3D解剖结构。但是，有两个问题可以防止有效培训3D医疗生成模型：（1）3D医学图像的获取和注释非常昂贵，导致培训图像不足，（2）大量参数是参与3D卷积。为了解决这两个问题，我们提出了一种名为3D Split＆Shuffle-Gan的新型GAN模型。为了解决3D数据稀缺问题，我们首先使用丰富的图像切片预先培训二维（2D）GAN模型，并夸大2D卷积权重以改善3D GAN的初始化。为GAN模型的生成器和鉴别器提出了新型的3D网络体系结构，以显着减少参数的数量，同时保持图像生成的质量。研究了许多体重通胀策略和参数有效的3D架构。对心脏（Stanford Aimi冠状动脉钙）和大脑（阿尔茨海默氏病神经成像计划）的实验表明，所提出的方法会导致改善的3D图像产生质量，参数较少。

生成的对抗网络（GAN）是在众多领域成功使用的一种强大的深度学习模型。它们属于一个称为生成方法的更广泛的家族，该家族通过从真实示例中学习样本分布来生成新数据。在临床背景下，与传统的生成方法相比，GAN在捕获空间复杂，非线性和潜在微妙的疾病作用方面表现出增强的能力。这篇综述评估了有关gan在各种神经系统疾病的成像研究中的应用的现有文献，包括阿尔茨海默氏病，脑肿瘤，脑老化和多发性硬化症。我们为每个应用程序提供了各种GAN方法的直观解释，并进一步讨论了在神经影像学中利用gans的主要挑战，开放问题以及有希望的未来方向。我们旨在通过强调如何利用gan来支持临床决策，并有助于更好地理解脑部疾病的结构和功能模式，从而弥合先进的深度学习方法和神经病学研究之间的差距。

生成对抗网络（GAN）具有许多潜在的医学成像应用，包括数据扩展，域适应和模型解释。由于图形处理单元（GPU）的记忆力有限，因此在低分辨率的医学图像上对当前的3D GAN模型进行了训练，因此这些模型要么无法扩展到高分辨率，要么容易出现斑驳的人工制品。在这项工作中，我们提出了一种新颖的端到端GAN体系结构，可以生成高分辨率3D图像。我们通过使用训练和推理之间的不同配置来实现这一目标。在训练过程中，我们采用了层次结构，该结构同时生成图像的低分辨率版本和高分辨率图像的随机选择子量。层次设计具有两个优点：首先，对高分辨率图像训练的记忆需求在子量之间摊销。此外，将高分辨率子体积固定在单个低分辨率图像上可确保子量化之间的解剖一致性。在推断期间，我们的模型可以直接生成完整的高分辨率图像。我们还将具有类似层次结构的编码器纳入模型中，以从图像中提取特征。 3D胸CT和脑MRI的实验表明，我们的方法在图像生成中的表现优于最新技术。我们还证明了所提出的模型在数据增强和临床相关特征提取中的临床应用。

It is well known that the performance of any classification model is effective if the dataset used for the training process and the test process satisfy some specific requirements. In other words, the more the dataset size is large, balanced, and representative, the more one can trust the proposed model's effectiveness and, consequently, the obtained results. Unfortunately, large-size anonymous datasets are generally not publicly available in biomedical applications, especially those dealing with pathological human face images. This concern makes using deep-learning-based approaches challenging to deploy and difficult to reproduce or verify some published results. In this paper, we suggest an efficient method to generate a realistic anonymous synthetic dataset of human faces with the attributes of acne disorders corresponding to three levels of severity (i.e. Mild, Moderate and Severe). Therefore, a specific hierarchy StyleGAN-based algorithm trained at distinct levels is considered. To evaluate the performance of the proposed scheme, we consider a CNN-based classification system, trained using the generated synthetic acneic face images and tested using authentic face images. Consequently, we show that an accuracy of 97,6\% is achieved using InceptionResNetv2. As a result, this work allows the scientific community to employ the generated synthetic dataset for any data processing application without restrictions on legal or ethical concerns. Moreover, this approach can also be extended to other applications requiring the generation of synthetic medical images. We can make the code and the generated dataset accessible for the scientific community.

The success of Deep Learning applications critically depends on the quality and scale of the underlying training data. Generative adversarial networks (GANs) can generate arbitrary large datasets, but diversity and fidelity are limited, which has recently been addressed by denoising diffusion probabilistic models (DDPMs) whose superiority has been demonstrated on natural images. In this study, we propose Medfusion, a conditional latent DDPM for medical images. We compare our DDPM-based model against GAN-based models, which constitute the current state-of-the-art in the medical domain. Medfusion was trained and compared with (i) StyleGan-3 on n=101,442 images from the AIROGS challenge dataset to generate fundoscopies with and without glaucoma, (ii) ProGAN on n=191,027 from the CheXpert dataset to generate radiographs with and without cardiomegaly and (iii) wGAN on n=19,557 images from the CRCMS dataset to generate histopathological images with and without microsatellite stability. In the AIROGS, CRMCS, and CheXpert datasets, Medfusion achieved lower (=better) FID than the GANs (11.63 versus 20.43, 30.03 versus 49.26, and 17.28 versus 84.31). Also, fidelity (precision) and diversity (recall) were higher (=better) for Medfusion in all three datasets. Our study shows that DDPM are a superior alternative to GANs for image synthesis in the medical domain.

The style-based GAN architecture (StyleGAN) yields state-of-the-art results in data-driven unconditional generative image modeling. We expose and analyze several of its characteristic artifacts, and propose changes in both model architecture and training methods to address them. In particular, we redesign the generator normalization, revisit progressive growing, and regularize the generator to encourage good conditioning in the mapping from latent codes to images. In addition to improving image quality, this path length regularizer yields the additional benefit that the generator becomes significantly easier to invert. This makes it possible to reliably attribute a generated image to a particular network. We furthermore visualize how well the generator utilizes its output resolution, and identify a capacity problem, motivating us to train larger models for additional quality improvements. Overall, our improved model redefines the state of the art in unconditional image modeling, both in terms of existing distribution quality metrics as well as perceived image quality.

近年来有条件的GAN已经成熟，并且能够产生高质量的现实形象。但是，计算资源和培训高质量的GAN所需的培训数据是巨大的，因此对这些模型的转移学习的研究是一个紧急话题。在本文中，我们探讨了从高质量预训练的无条件GAN到有条件的GAN的转移。为此，我们提出了基于HyperNetwork的自适应权重调制。此外，我们介绍了一个自我初始化过程，不需要任何真实数据才能初始化HyperNetwork参数。为了进一步提高知识转移的样本效率，我们建议使用自我监督（对比）损失来改善GaN判别者。在广泛的实验中，我们验证了多个标准基准上的Hypernetworks，自我初始化和对比损失的效率。

Our goal with this survey is to provide an overview of the state of the art deep learning technologies for face generation and editing. We will cover popular latest architectures and discuss key ideas that make them work, such as inversion, latent representation, loss functions, training procedures, editing methods, and cross domain style transfer. We particularly focus on GAN-based architectures that have culminated in the StyleGAN approaches, which allow generation of high-quality face images and offer rich interfaces for controllable semantics editing and preserving photo quality. We aim to provide an entry point into the field for readers that have basic knowledge about the field of deep learning and are looking for an accessible introduction and overview.

The introduction of high-quality image generation models, particularly the StyleGAN family, provides a powerful tool to synthesize and manipulate images. However, existing models are built upon high-quality (HQ) data as desired outputs, making them unfit for in-the-wild low-quality (LQ) images, which are common inputs for manipulation. In this work, we bridge this gap by proposing a novel GAN structure that allows for generating images with controllable quality. The network can synthesize various image degradation and restore the sharp image via a quality control code. Our proposed QC-StyleGAN can directly edit LQ images without altering their quality by applying GAN inversion and manipulation techniques. It also provides for free an image restoration solution that can handle various degradations, including noise, blur, compression artifacts, and their mixtures. Finally, we demonstrate numerous other applications such as image degradation synthesis, transfer, and interpolation.

In biomedical image analysis, the applicability of deep learning methods is directly impacted by the quantity of image data available. This is due to deep learning models requiring large image datasets to provide high-level performance. Generative Adversarial Networks (GANs) have been widely utilized to address data limitations through the generation of synthetic biomedical images. GANs consist of two models. The generator, a model that learns how to produce synthetic images based on the feedback it receives. The discriminator, a model that classifies an image as synthetic or real and provides feedback to the generator. Throughout the training process, a GAN can experience several technical challenges that impede the generation of suitable synthetic imagery. First, the mode collapse problem whereby the generator either produces an identical image or produces a uniform image from distinct input features. Second, the non-convergence problem whereby the gradient descent optimizer fails to reach a Nash equilibrium. Thirdly, the vanishing gradient problem whereby unstable training behavior occurs due to the discriminator achieving optimal classification performance resulting in no meaningful feedback being provided to the generator. These problems result in the production of synthetic imagery that is blurry, unrealistic, and less diverse. To date, there has been no survey article outlining the impact of these technical challenges in the context of the biomedical imagery domain. This work presents a review and taxonomy based on solutions to the training problems of GANs in the biomedical imaging domain. This survey highlights important challenges and outlines future research directions about the training of GANs in the domain of biomedical imagery.

In this work, we are dedicated to text-guided image generation and propose a novel framework, i.e., CLIP2GAN, by leveraging CLIP model and StyleGAN. The key idea of our CLIP2GAN is to bridge the output feature embedding space of CLIP and the input latent space of StyleGAN, which is realized by introducing a mapping network. In the training stage, we encode an image with CLIP and map the output feature to a latent code, which is further used to reconstruct the image. In this way, the mapping network is optimized in a self-supervised learning way. In the inference stage, since CLIP can embed both image and text into a shared feature embedding space, we replace CLIP image encoder in the training architecture with CLIP text encoder, while keeping the following mapping network as well as StyleGAN model. As a result, we can flexibly input a text description to generate an image. Moreover, by simply adding mapped text features of an attribute to a mapped CLIP image feature, we can effectively edit the attribute to the image. Extensive experiments demonstrate the superior performance of our proposed CLIP2GAN compared to previous methods.

GAN的进展使高分辨率的感性质量形象产生了产生。 stylegans允许通过数学操作对W/W+空间中的潜在样式向量进行数学操作进行引人入胜的属性修改，从而有效调节生成器的丰富层次结构表示。最近，此类操作已被推广到原始StyleGan纸中的属性交换之外，以包括插值。尽管StyleGans有许多重大改进，但仍被认为会产生不自然的图像。生成的图像的质量基于两个假设。 （a）生成器学到的层次表示的丰富性，以及（b）样式空间的线性和平滑度。在这项工作中，我们提出了一个层次的语义正常化程序（HSR），该层次正常化程序将生成器学到的层次表示与大量数据学到的相应的强大功能保持一致。 HSR不仅可以改善发电机的表示，还可以改善潜在风格空间的线性和平滑度，从而导致产生更自然的样式编辑的图像。为了证明线性改善，我们提出了一种新型的度量 - 属性线性评分（ALS）。通过改善感知路径长度（PPL）度量的改善，在不同的标准数据集中平均16.19％的不自然图像的生成显着降低，同时改善了属性编辑任务中属性变化的线性变化。

气候变化正在增加有害藻华（HAB）的频率和严重程度，这些藻类在水产养殖场中造成大量鱼类死亡。这有助于海洋污染和温室气体（GHG）的排放，因为死鱼要么被倾倒到海洋中，要么被带到垃圾填埋场，进而对气候产生负面影响。当前，列举有害藻类和其他浮游植物的标准方法是在显微镜下手动观察并对其进行计数。这是一个耗时，乏味且容易出错的过程，导致农民的管理决定妥协。因此，自动化此过程以进行快速准确的HAB监控非常有帮助。但是，这需要大量且多样化的浮游植物图像数据集，并且这些数据集很难快速生产。在这项工作中，我们探讨了产生新型高分辨率的光真逼真的合成浮游植物图像的可行性，这些图像包含相同图像中的多个物种，并且给定了一小部分真实图像。为此，我们采用生成的对抗网络（GAN）来生成合成图像。我们使用标准图像质量指标评估了三种不同的GAN架构：ProjectedGan，Fastgan和styleganv2。我们从经验上显示了仅使用961个真实图像的训练数据集的高保真合成浮游植物图像的产生。因此，这项工作证明了甘斯从小型培训数据集中创建大型浮游植物的大型合成数据集的能力，从而朝着可持续的系统监测有害藻类绽放迈出了关键的一步。

组织病理学图像合成的现有深网无法为聚类核生成准确的边界，并且无法输出与不同器官一致的图像样式。为了解决这些问题，我们提出了一种样式引导的实例自适应标准化（SIAN），以合成不同器官的逼真的颜色分布和纹理。 Sian包含四个阶段：语义，风格化，实例化和调制。这四个阶段共同起作用，并集成到生成网络中，以嵌入图像语义，样式和实例级级边界。实验结果证明了所有组件在Sian中的有效性，并表明所提出的方法比使用Frechet Inception Inception距离（FID），结构相似性指数（SSIM），检测质量胜过组织病理学图像合成的最新条件gan。 （DQ），分割质量（SQ）和圆锥体质量（PQ）。此外，通过合并使用Sian产生的合成图像，可以显着改善分割网络的性能。

当今的生成模型能够综合高保真图像，但是每个模型都专门研究特定的目标域。这增加了模型合并的需求：将两个或多个预贴的生成模型组合到单个统一模型中。在这项工作中，我们解决了模型合并的问题，鉴于在现实世界中经常出现的两个限制：（1）无法访问原始培训数据，并且（2）没有增加神经网络的大小。据我们所知，到目前为止尚未研究在这些约束下合并的模型。我们提出了一种新颖的两阶段解决方案。在第一阶段，我们将所有模型的权重转换为相同的参数空间，通过我们项模型生根的技术。在第二阶段，我们仅使用原始训练的模型生成的数据将其平均重量平均并为每个特定域进行微调来合并。我们证明我们的方法优于基线方法和现有的转移学习技术，并研究了几种应用。

图像到图像翻译（I2I）是一个充满挑战的计算机视觉问题，用于多个任务的众多域。最近，眼科成为I2i的应用迅速增加的主要领域之一。一种这样的应用是合成视网膜光学相干断层（OCT）扫描的产生。现有的I2I方法需要培训多种模型，将图像从正常扫描转换为特定病理学：限制由于它们的复杂性而对这些模型的使用。要解决此问题，我们提出了一个无监督的多域I2I网络，具有预先培训的样式编码器，可将一个域中的视网膜OCT图像转换为多个域。我们假设图像分裂到域不变内容和域特定的样式代码，并预先培训这些样式代码。所执行的实验表明，所提出的模型优于Munit和Cyclangan合成不同的病理扫描等最先进的模型。

Generative Adversarial Networks (GANs) were introduced by Goodfellow in 2014, and since then have become popular for constructing generative artificial intelligence models. However, the drawbacks of such networks are numerous, like their longer training times, their sensitivity to hyperparameter tuning, several types of loss and optimization functions and other difficulties like mode collapse. Current applications of GANs include generating photo-realistic human faces, animals and objects. However, I wanted to explore the artistic ability of GANs in more detail, by using existing models and learning from them. This dissertation covers the basics of neural networks and works its way up to the particular aspects of GANs, together with experimentation and modification of existing available models, from least complex to most. The intention is to see if state of the art GANs (specifically StyleGAN2) can generate album art covers and if it is possible to tailor them by genre. This was attempted by first familiarizing myself with 3 existing GANs architectures, including the state of the art StyleGAN2. The StyleGAN2 code was used to train a model with a dataset containing 80K album cover images, then used to style images by picking curated images and mixing their styles.

Recent 3D-aware GANs rely on volumetric rendering techniques to disentangle the pose and appearance of objects, de facto generating entire 3D volumes rather than single-view 2D images from a latent code. Complex image editing tasks can be performed in standard 2D-based GANs (e.g., StyleGAN models) as manipulation of latent dimensions. However, to the best of our knowledge, similar properties have only been partially explored for 3D-aware GAN models. This work aims to fill this gap by showing the limitations of existing methods and proposing LatentSwap3D, a model-agnostic approach designed to enable attribute editing in the latent space of pre-trained 3D-aware GANs. We first identify the most relevant dimensions in the latent space of the model controlling the targeted attribute by relying on the feature importance ranking of a random forest classifier. Then, to apply the transformation, we swap the top-K most relevant latent dimensions of the image being edited with an image exhibiting the desired attribute. Despite its simplicity, LatentSwap3D provides remarkable semantic edits in a disentangled manner and outperforms alternative approaches both qualitatively and quantitatively. We demonstrate our semantic edit approach on various 3D-aware generative models such as pi-GAN, GIRAFFE, StyleSDF, MVCGAN, EG3D and VolumeGAN, and on diverse datasets, such as FFHQ, AFHQ, Cats, MetFaces, and CompCars. The project page can be found: \url{https://enisimsar.github.io/latentswap3d/}.