Ludtke S J, Baldwin P R, Chiu W
Verna and Marrs McLean Department of Biochemistry, National Center for Macromolecular Imaging, Houston, Texas 77030, USA.
J Struct Biol. 1999 Dec 1;128(1):82-97. doi: 10.1006/jsbi.1999.4174.
We present EMAN (Electron Micrograph ANalysis), a software package for performing semiautomated single-particle reconstructions from transmission electron micrographs. The goal of this project is to provide software capable of performing single-particle reconstructions beyond 10 A as such high-resolution data become available. A complete single-particle reconstruction algorithm is implemented. Options are available to generate an initial model for particles with no symmetry, a single axis of rotational symmetry, or icosahedral symmetry. Model refinement is an iterative process, which utilizes classification by model-based projection matching. CTF (contrast transfer function) parameters are determined using a new paradigm in which data from multiple micrographs are fit simultaneously. Amplitude and phase CTF correction is then performed automatically as part of the refinement loop. A graphical user interface is provided, so even those with little image processing experience will be able to begin performing reconstructions. Advanced users can directly use the lower level shell commands and even expand the package utilizing EMAN's extensive image-processing library. The package was written from scratch in C++ and is provided free of charge on our Web site. We present an overview of the package as well as several conformance tests with simulated data.
我们展示了EMAN（电子显微镜图像分析），这是一个用于从透射电子显微镜图像进行半自动单颗粒重建的软件包。该项目的目标是在有高分辨率数据可用时，提供能够进行超过10埃分辨率的单颗粒重建的软件。实现了完整的单颗粒重建算法。有多种选项可用于为无对称性、单轴对称性或二十面体对称性的颗粒生成初始模型。模型精修是一个迭代过程，它利用基于模型的投影匹配进行分类。使用一种新的范式来确定CTF（对比度传递函数）参数，即同时拟合来自多张显微照片的数据。然后，作为精修循环的一部分，自动进行幅度和相位CTF校正。提供了图形用户界面，因此即使是图像处理经验很少的人也能够开始进行重建。高级用户可以直接使用较低级别的外壳命令，甚至利用EMAN广泛的图像处理库来扩展该软件包。该软件包完全用C++编写，并在我们的网站上免费提供。我们概述了该软件包以及几个对模拟数据的一致性测试。
