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![[Figure 3]](ij5005fig3mag.jpg)
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Figure 3
Robust CTF estimation from tomographic tilted projections obtained by leveraging tilt-geometry parameters determined during tilt series alignment. (a) Left: a 2D power spectrum from a 60° tilt projection and CTF estimation results obtained using CTFFIND4 (Rohou & Grigorieff, 2015  ), which is designed to work on untitled images, shows only the first few rings of the CTF. Right: radial average of the 2D power spectrum (red line), theoretical CTF curve (green dashed line) and corresponding CTF-fit curve measuring the similarity between the red and green curves (blue line). (b) Corresponding power spectrum and CTF estimation profiles for the image shown in (a) using the tilted CTF estimation strategy that uses information from tilt series alignment to successfully recover the Thon ring pattern extending to higher resolution. (c) CTF-fit resolution cutoff as a function of the tilt angle. Unlike strategies that rely on averaging consecutive tilts to improve the SNR (Mastronarde & Held, 2017), this constrained approach produces accurate per-tilt defocus estimates throughout the ±60° tilt range. |
![[Figure 3]](ij5005fig3.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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