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Figure 3
Comparison of contrast transfer function (CTF) estimation for 4K (a: native), 8K (b: super resolution) and 8K (c: PASR-preprocessed 4K micrographs) from the same micrograph. The original micrograph was collected using the EER file format and converted to either 4K TIFF or 8K TIFF using the RELION function relion_convert_to_tiff. CTFFIND was used to calculate parameters for each with the following settings: FFT box size: 512 pixels, minimum resolution: 30 Å, maximum resolution: 3 Å, minimum defocus: 1000 Å, maximum defocus: 50 000 Å, defocus step size: 100 Å. For each condition, the power spectrum is displayed, showing clear Thon rings, along with the CTFFIND-derived rotational average and simulated fit (top). Underneath, 1D diagnostic plots from CTFFIND are shown, demonstrating highly similar calculated defocus and astigmatism values. The sampling frequency of the 4K micrograph is 1.912 Å pixel−1, while for the super resolution and PASR micrographs the sampling frequency is 0.956 Å pixel−1.

IUCrJ
Volume 13| Part 5| September 2026| Pages 589-605
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526005348