Quantitative Imaging Group, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Ultramicroscopy. 2012 Jul;118:26-34. doi: 10.1016/j.ultramic.2012.05.002. Epub 2012 May 14.
We have developed new methods for contrast transfer function (CTF) correction of tilted and/or thick specimens. In order to achieve higher resolutions in cryo-electron tomography (CryoET), it is necessary to account for the defocus gradient on a tilted specimen and possibly the defocus gradient within a thick specimen. CTF correction methods which account for these defocus differences have recently gained interest. However, there is no global CTF correction method available to this date (to process the entire field-of-view at once) which can use different inverse filters, e.g. phase-flipping or Wiener filter, and which can do so within a reasonable time for realistic image sizes. We show that the CTF correction methods presented in this paper correctly account for the spatially varying defocus, can employ different inverse filters and are significantly faster (>50×) than existing methods. We provide proof-of-principle implementations of all the presented CTF correction methods online.
我们开发了新的方法来校正倾斜和/或厚的样品的对比传递函数（CTF）。为了在冷冻电子断层扫描（CryoET）中实现更高的分辨率，有必要考虑倾斜样品上的离焦梯度，并且可能需要考虑厚样品内的离焦梯度。最近，人们对考虑这些离焦差异的 CTF 校正方法产生了兴趣。然而，到目前为止，还没有一种全局 CTF 校正方法（一次处理整个视场）可以使用不同的逆滤波器，例如相位翻转或维纳滤波器，并且可以在合理的时间内处理现实图像尺寸。我们表明，本文提出的 CTF 校正方法可以正确地考虑空间变化的离焦，可以使用不同的逆滤波器，并且比现有的方法快得多（>50 倍）。我们在线提供了所有提出的 CTF 校正方法的原理证明实现。
