The w-effect in interferometric imaging: from a fast sparse measurement operator to superresolution
The w-effect in interferometric imaging: from a fast sparse measurement operator to superresolution
复制标题
干涉成像中的 w 效应：从快速稀疏测量算子到超分辨率
DOI：
10.1093/mnras/stx1775
复制
发表时间：
2017
影响因子：
4.8
通讯作者：
Y. Wiaux
中科院分区：
文献类型：
--
作者：
A. Dabbech;L. Wolz;L. Pratley;J. McEwen;Y. Wiaux
现代射电望远镜，如平方公里阵列（SKA），将在大视场范围内探测射电天空，这导致天空图像的大w调制。这种效应使测量的活力与仔细观察的图像之间的关系复杂化。在算法方面，它会产生大量的内存和计算时间需求。然而，就天空图像的重建质量而言，它可以是一种祝福。近年来，一些工作表明，大的w调制促进扩频效果。在压缩感知框架内，这种效应增加了要恢复的信号的感知基础和稀疏基础之间的不相干性，从而导致对天空图像的更好估计。在本文中，我们重新审视了在现实环境中使用凸优化的w投影方法，其中测量运算符将傅立叶中的w项与去网格化内核耦合起来。我们提供稀疏，因此快速，模型的傅立叶部分的测量算子，通过自适应稀疏化程序。因此，存储器需求和计算成本被显著减轻，代价是在无线电干涉测量数据模型上引入误差。我们提出了第一次调查的稀疏变量的测量算子对图像重建质量的影响。最后，我们分析了与w调制的扩频效应相关的有趣的超分辨率潜力，并通过仿真展示了它。我们的C++代码可以在GitHub上在线获得。
Modern radio telescopes, such as the Square Kilometre Array (SKA), will probe the radio sky over large fields-of-view, which results in large w-modulations of the sky image. This effect complicates the relationship between the measured visibilities and the image under scrutiny. In algorithmic terms, it gives rise to massive memory and computational time requirements. Yet, it can be a blessing in terms of reconstruction quality of the sky image. In recent years, several works have shown that large w-modulations promote the spread spectrum effect. Within the compressive sensing framework, this effect increases the incoherence between the sensing basis and the sparsity basis of the signal to be recovered, leading to better estimation of the sky image. In this article, we revisit the w-projection approach using convex optimisation in realistic settings, where the measurement operator couples the w-terms in Fourier and the de-gridding kernels. We provide sparse, thus fast, models of the Fourier part of the measurement operator through adaptive sparsification procedures. Consequently, memory requirements and computational cost are significantly alleviated, at the expense of introducing errors on the radio-interferometric data model. We present a first investigation of the impact of the sparse variants of the measurement operator on the image reconstruction quality. We finally analyse the interesting super-resolution potential associated with the spread spectrum effect of the w-modulation, and showcase it through simulations. Our C++ code is available online on GitHub.
用于无线电干涉成像的加速分裂算法：当自然和均匀加权满足时
DOI：
--
发表时间：
2017
期刊：
ArXiv e-prints
影响因子：
--
作者：
Onose Alexandru
通讯作者：
Onose Alexandru