Direct model fitting to combine dithered ACS images
Direct model fitting to combine dithered ACS images
复制标题
直接模型拟合以组合抖动的 ACS 图像
DOI：
10.1051/0004-6361/201321347
复制
发表时间：
2013
影响因子：
6.5
通讯作者：
O. Wucknitz
中科院分区：
文献类型：
--
作者：
H. Mahmoudian;O. Wucknitz
利用“抖动”技术可以恢复欠采样CCD相机图像中丢失的信息。为了在小于一个像素的尺度上记录结构，用亚像素位移拍摄了许多次曝光。结合这些曝光的标准方法是“毛毛雨”，在反转位移（包括旋转和扭曲）后取平均值。更复杂的方法可用来产生，例如，奈奎斯特采样表示的带限输入。虽然这些方法产生的组合图像可以是高质量的，但它们作为引力透镜前向建模技术的输入仍然不是最佳的，因为残余的伪影仍然以不可预测的方式影响建模结果。在本文中，我们提出了一种全面的建模方法，该方法考虑了抖动和透镜，而没有组合图像的中间产物。作为一个构建块，我们引入了一种替代方法，通过直接模型拟合和包含正则化约束的最小二乘方法来组合抖动图像。我们用模拟数据和真实数据进行了测试，证明了结果的质量。引力透镜的附加效应和与仪器点扩展函数的卷积可以自然地包括在内，避免了先前程序可能出现的系统误差。
The information lost in images of undersampled CCD cameras can be recovered with the technique of “dithering”. A number of subexposures is taken with sub-pixel shifts in order to record structures on scales smaller than a pixel. The standard method to combine such exposures, “Drizzle”, averages after reversing the displacements, including rotations and distortions. More sophisticated methods are available to produce, e.g., Nyquist sampled representations of band-limited inputs. While the combined images produced by these methods can be of high quality, their use as input for forward-modelling techniques in gravitational lensing is still not optimal, because the residual artefacts still affect the modelling results in unpredictable ways. In this paper we argue for an overall modelling approach that takes into account the dithering and the lensing without the intermediate product of a combined image. As one building block we introduce an alternative approach to combine dithered images by direct model fitting with a least-squares approach including a regularization constraint. We present tests with simulated and real data that show the quality of the results. The additional effects of gravitational lensing and the convolution with an instrumental point spread function can be included in a natural way, avoiding the possible systematic errors of previous procedures.