The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.

In this work, we propose a novel image reconstruction framework that directly learns a neural implicit representation in k-space for ECG-triggered non-Cartesian Cardiac Magnetic Resonance Imaging (CMR). While existing methods bin acquired data from neighboring time points to reconstruct one phase of the cardiac motion, our framework allows for a continuous, binning-free, and subject-specific k-space representation.We assign a unique coordinate that consists of time, coil index, and frequency domain location to each sampled k-space point. We then learn the subject-specific mapping from these unique coordinates to k-space intensities using a multi-layer perceptron with frequency domain regularization. During inference, we obtain a complete k-space for Cartesian coordinates and an arbitrary temporal resolution. A simple inverse Fourier transform recovers the image, eliminating the need for density compensation and costly non-uniform Fourier transforms for non-Cartesian data. This novel imaging framework was tested on 42 radially sampled datasets from 6 subjects. The proposed method outperforms other techniques qualitatively and quantitatively using data from four and one heartbeat(s) and 30 cardiac phases. Our results for one heartbeat reconstruction of 50 cardiac phases show improved artifact removal and spatio-temporal resolution, leveraging the potential for real-time CMR.

Quantifying the perceptual similarity of two images is a long-standing problem in low-level computer vision. The natural image domain commonly relies on supervised learning, e.g., a pre-trained VGG, to obtain a latent representation. However, due to domain shift, pre-trained models from the natural image domain might not apply to other image domains, such as medical imaging. Notably, in medical imaging, evaluating the perceptual similarity is exclusively performed by specialists trained extensively in diverse medical fields. Thus, medical imaging remains devoid of task-specific, objective perceptual measures. This work answers the question: Is it necessary to rely on supervised learning to obtain an effective representation that could measure perceptual similarity, or is self-supervision sufficient? To understand whether recent contrastive self-supervised representation (CSR) may come to the rescue, we start with natural images and systematically evaluate CSR as a metric across numerous contemporary architectures and tasks and compare them with existing methods. We find that in the natural image domain, CSR behaves on par with the supervised one on several perceptual tests as a metric, and in the medical domain, CSR better quantifies perceptual similarity concerning the experts' ratings. We also demonstrate that CSR can significantly improve image quality in two image synthesis tasks. Finally, our extensive results suggest that perceptuality is an emergent property of CSR, which can be adapted to many image domains without requiring annotations.

在本文中，我们考虑了神经视频压缩（NVC）中位分配的问题。由于帧参考结构，使用相同的R-D（速率）权衡参数$ \ lambda $的当前NVC方法是次优的，这带来了位分配的需求。与以前基于启发式和经验R-D模型的方法不同，我们建议通过基于梯度的优化解决此问题。具体而言，我们首先提出了一种基于半损坏的变异推理（SAVI）的连续位实现方法。然后，我们通过更改SAVI目标，使用迭代优化提出了一个像素级隐式分配方法。此外，我们基于NVC的可区分特征得出了精确的R-D模型。我们通过使用精确的R-D模型证明其等效性与位分配的等效性来展示我们的方法的最佳性。实验结果表明，我们的方法显着改善了NVC方法，并且胜过现有的位分配方法。我们的方法是所有可区分NVC方法的插件，并且可以直接在现有的预训练模型上采用。

预先训练的图像文本模型（如剪辑）已经证明了从大规模的Web收集的图像文本数据中学到的视觉表示的强大力量。鉴于学习良好的视觉特征，一些现有的作品将图像表示转移到视频域并取得良好的结果。但是，如何利用图像语言预训练的模型（例如，剪辑）进行视频培训（后培训）仍在探索。在本文中，我们研究了两个问题：1）阻碍后期剪辑的因素是什么因素，以进一步提高视频语言任务的性能？ 2）如何减轻这些因素的影响？通过一系列比较实验和分析，我们发现语言源之间的数据量表和域间隙具有很大的影响。由这些动机，我们提出了一种配备了视频代理机制的Omnisource跨模式学习方法，即剪辑，即剪辑VIP。广泛的结果表明，我们的方法可以提高视频检索的剪辑的性能。我们的模型还可以在包括MSR-VTT，DIDEMO，LSMDC和ActivityNet在内的各种数据集上实现SOTA结果。我们在https://github.com/microsoft/xpretrain/tree/main/main/main/clip-vip上发布了代码和预训练的剪辑模型。

在各种基于学习的图像恢复任务（例如图像降解和图像超分辨率）中，降解表示形式被广泛用于建模降解过程并处理复杂的降解模式。但是，在基于学习的图像deblurring中，它们的探索程度较低，因为在现实世界中挑战性的情况下，模糊内核估计不能很好地表现。我们认为，对于图像降低的降解表示形式是特别必要的，因为模糊模式通常显示出比噪声模式或高频纹理更大的变化。在本文中，我们提出了一个框架来学习模糊图像的空间自适应降解表示。提出了一种新颖的联合图像re毁和脱蓝色的学习过程，以提高降解表示的表现力。为了使学习的降解表示有效地启动和降解，我们提出了一个多尺度退化注入网络（MSDI-NET），以将它们集成到神经网络中。通过集成，MSDI-NET可以适应各种复杂的模糊模式。 GoPro和Realblur数据集上的实验表明，我们提出的具有学识渊博的退化表示形式的Deblurring框架优于最先进的方法，具有吸引人的改进。该代码在https://github.com/dasongli1/learning_degradation上发布。

图像表示对于许多视觉任务至关重要。最近的一项研究，即局部隐式图像函数（LIIF），而不是用2D阵列代替图像，而是将图像表示为连续函数，其中像素值是通过使用相应的坐标作为输入来扩展的。由于其连续的性质，可以为任意规模的图像超分辨率任务采用LIIF，从而为各种提高因素提供了一个有效和有效的模型。但是，Liif通常遭受边缘周围的结构扭曲和响起的伪影，主要是因为所有像素共享相同的模型，因此忽略了图像的局部特性。在本文中，我们提出了一种新颖的自适应局部图像功能（A-LIIF）来减轻此问题。具体而言，我们的A-LIIF由两个主要组成部分组成：编码器和扩展网络。前者捕获了跨尺度的图像特征，而后者通过多个局部隐式图像函数的加权组合进行了连续升级函数。因此，我们的A-LIIF可以更准确地重建高频纹理和结构。多个基准数据集的实验验证了我们方法的有效性。我们的代码可在\ url {https://github.com/leehw-thu/a-liif}上找到。

与传统方法相比，学到的图像压缩已在PSNR和MS-SSIM中取得了非凡的速率延伸性能。但是，它遭受了密集的计算，这对于现实世界的应用是无法忍受的，目前导致其工业应用有限。在本文中，我们将神经体系结构搜索（NAS）介绍到具有较低延迟的更有效网络，并利用量化以加速推理过程。同时，已经为提高效率而做出了工程努力。使用PSNR和MS-SSIM的混合损失以更好的视觉质量进行了优化，我们获得的MSSIM比JPEG，JPEG XL和AVIF在所有比特率上都高得多，而JPEG XL和AVIF之间的PSNR则获得了PSNR。与JPEG-Turbo相比，我们的LIC的软件实施实现了可比较甚至更快的推理速度，而多次比JPEG XL和AVIF快。此外，我们的LIC实施达到了145 fps的惊人吞吐量，用于编码为208 fps，用于在Tesla T4 GPU上解码1080p图像。在CPU上，我们实施的延迟与JPEG XL相当。

3D肺部片段的重建在肺癌的外科治疗计划中起着重要作用，这有助于保存肺功能并有助于确保低复发率。但是，在深度学习时代，肺部段的自动重建仍未得到探索。在本文中，我们研究了是什么使肺部段自动重建。首先，我们在临床和几何上表达了肺部段的解剖学定义，并提出了遵守这些定义的评估指标。其次，我们提出了脉冲（隐式肺部段），这是一种旨在肺部段重建的深层隐式表面模型。通过脉冲自动重建肺部段的指标和视觉吸引力是准确的。与规范分割方法相比，冲动输出连续预测任意分辨率具有较高的训练效率和更少的参数。最后，我们尝试不同的网络输入，以分析肺部段重建任务中重要的事情。我们的代码可在https://github.com/m3dv/impulse上找到。

医疗图像合成引起了人们的关注，因为它可能会产生缺失的图像数据，改善诊断并受益于许多下游任务。但是，到目前为止，开发的合成模型并不适应显示域移位的看不见的数据分布，从而限制了其在临床常规中的适用性。这项工作着重于探索3D图像到图像合成模型的域适应性（DA）。首先，我们强调了分类，分割和合成模型之间DA的技术差异。其次，我们提出了一种基于近似3D分布的2D变异自动编码器的新型有效适应方法。第三，我们介绍了有关适应数据量和关键超参数量的影响的经验研究。我们的结果表明，所提出的方法可以显着提高3D设置中未见域的合成精度。该代码可在https://github.com/winstonhutiger/2d_vae_uda_for_3d_sythesis上公开获得。